I use the inbuilt calendar to sync with Google Calendar and Google
contacts' birthdays plus UK holidays.
If I add an event in tb/Bb it syncs immediately to Google Calendar on
Windows and my android mobile.
If, however I add en entry via my mobile, it syncs to Google on Windows,
but NOT on my Tb/Bb calendar.
Why?

Latest Tb or Bb, Windows 10, Lightning and Provider installed.

--
Jim the Geordie

Jim the Geordie <jim@jimXscott.co.uk> wrote:

> I use the inbuilt calendar to sync with Google Calendar and Google
> contacts' birthdays plus UK holidays.
> If I add an event in tb/Bb it syncs immediately to Google Calendar on
> Windows and my android mobile.
> If, however I add en entry via my mobile, it syncs to Google on Windows,
> but NOT on my Tb/Bb calendar.
> Why?
>
> Latest Tb or Bb, Windows 10, Lightning and Provider installed.

Unless there was a change, Thunderbird never supported the Calendar API
from Google. Instead Tbird relied on the vCal protocol, just like it
relies on vCard for contacts. The Google APIs allow direct access to
account data versus having to export/import using vCal or vCard.

https://developers.google.com/gmail/api/guides
https://developers.google.com/calendar/api/guides/overview
https://developers.google.com/people

Google apps can, and often do, use the Google APIs to access account
data. Everyone else has to use the standard (non-proprietary)
POP/IMAP/SMTP, vCal, or vCard protocols.

https://en.wikipedia.org/wiki/Post_Office_Protocol
https://en.wikipedia.org/wiki/Internet_Message_Access_Protocol
https://en.wikipedia.org/wiki/ICalendar
https://en.wikipedia.org/wiki/VCard

What is "Google on Windows"? Google is a company name, not a product
name.

What is "Provider"? Is that some add-on you installed into Tbird?
Maybe this one?

https://addons.thunderbird.net/en-US/thunderbird/addon/provider-for-google-calendar

More info at the author's Github page at:

https://github.com/kewisch/gdata-provider/wiki

That author is using the Google APIs to access Google account data.
However, my recollection is that to use the Google APIs means you need
to have a Google dev project, and those get a limited quota of many
accesses are allowed per day. If there are enough users of the project
issuing API requests, the quota gets consumed. You have to wait until
the project gets its next allocation of quota, or the project owner buys
more quota.

I ran into this with my choice of mail client: eM Client. Besides
POP/IMAP/SMTP protocols, it also supports Google's APIs (mail, contacts,
calendar). However, users started reporting getting errors in the logs
("exceeded API quota"). Took a couple months before the company paid
for more quota, but the little they bought was quickly consumed, and
users got the same failures again. As a product gets more popular,
there are more users of it, and more API requests, so the quota gets
consumed, and the author has to keep buying more and more. Particularly
difficult when the product is free to keep digging deeper into own's own
pockets to pay for more quota.

Check if the add-on has its own logging function. If so, look into its
logs to see if there are "exceeded API quota" errors. You could ask the
author in his Github Discussions section how much quota he gets for his
Google dev project. The defaults sound huge until you realize that a
single user could be issuing hundreds of requests per transaction and
over the course of a day and day after day, and as the product gets
popular then magnify all those thousands of request by all those users.

Google doesn't put a limit on API requests on their own apps using
Google Workspace projects. Microsoft can afford to dole out a wad of
money to get more API quota to accomodate an ever increasing number of
users all consuming the quota.

https://hiverhq.com/blog/gmail-and-google-apps-limits-every-admin-should-know#Usage

In article <1i1k4tjpfz2yd$.dlg@v.nguard.lh>, V@nguard.LH says...
>
> Jim the Geordie <jim@jimXscott.co.uk> wrote:
>
> > I use the inbuilt calendar to sync with Google Calendar and Google
> > contacts' birthdays plus UK holidays.
> > If I add an event in tb/Bb it syncs immediately to Google Calendar on
> > Windows and my android mobile.
> > If, however I add en entry via my mobile, it syncs to Google on Windows,
> > but NOT on my Tb/Bb calendar.
> > Why?
> >
> > Latest Tb or Bb, Windows 10, Lightning and Provider installed.
>
> Unless there was a change, Thunderbird never supported the Calendar API
> from Google. Instead Tbird relied on the vCal protocol, just like it
> relies on vCard for contacts. The Google APIs allow direct access to
> account data versus having to export/import using vCal or vCard.
>
> https://developers.google.com/gmail/api/guides
> https://developers.google.com/calendar/api/guides/overview
> https://developers.google.com/people
>
> Google apps can, and often do, use the Google APIs to access account
> data. Everyone else has to use the standard (non-proprietary)
> POP/IMAP/SMTP, vCal, or vCard protocols.
>
> https://en.wikipedia.org/wiki/Post_Office_Protocol
> https://en.wikipedia.org/wiki/Internet_Message_Access_Protocol
> https://en.wikipedia.org/wiki/ICalendar
> https://en.wikipedia.org/wiki/VCard
>
> What is "Google on Windows"? Google is a company name, not a product
> name.

Google calendar. You knew that so stop being so pedantic.
>
> What is "Provider"? Is that some add-on you installed into Tbird?
> Maybe this one?
>
> https://addons.thunderbird.net/en-US/thunderbird/addon/provider-for-google-calendar

Yes.
Have you ever used Thunderbird?
If not why are you posting in this group?
>
> More info at the author's Github page at:
>
> https://github.com/kewisch/gdata-provider/wiki
>
> That author is using the Google APIs to access Google account data.
> However, my recollection is that to use the Google APIs means you need
> to have a Google dev project, and those get a limited quota of many
> accesses are allowed per day. If there are enough users of the project
> issuing API requests, the quota gets consumed. You have to wait until
> the project gets its next allocation of quota, or the project owner buys
> more quota.

Follow-up
I found it works if I restart Betterbird (my preferred option), instead
of using the synchronize tab.
Hey ho!

--
Jim the Geordie