Calendar Sync from and to Hotmail/Outlook is broken

[nww02]

Your environment

Linux Mint 21.2

TbSync version: 4.8
TBSync for EAS version: 4.8 (Latest)
Thunderbird version: 115.9.0 (64-bit)

Expected behavior

When I hit "Sync" any events I have created in my Outlook App or Outlook Calendar should appear in Thunderbird.

When I hit "Sync", any events I have created in Thunderbird using the Outlook calendar (e.g. "Birthdays") should appear on my Outlook App or Outlook Calendar page also on the Birthdays Calendar.

When I hit "Sync" any events I have permanently deleted in Thunderbird should delete from my Outlook App or Outlook Calendar Page.

All dates should align between the Outlook App and Thunderbird.

Actual behavior

When I hit "Sync", the events I have created in my Outlook App are downloaded to Thunderbird, but are on the wrong dates.
For example I have a birthday online for Tuesday August 13th 2024. It appeared in Thunderbird on Wednesday 21st February 2024. Another Birthday which is Monday 1st of January 2024 appears in Thunderbird on Tuesday 9th April 2024, alongside another public holiday "New Year's Day". Therefore the mapping of online date to Thunderbird date is not random.

When I hit "Sync", any events I have created in any calendar (including Birthdays) does NOT appear on the online Outlook Calendar.

When I hit "Sync", any events I have permanently deleted in Thunderbird do NOT delete from the online Outlook Calendar.

None of the dates align, but events that happen on the same day are moved to the SAME other wrong day.

Steps to reproduce

...

When I first set up the account, it gave me the "Could not find EAS version" error which is the subject of another issue. I resolved that by following your advice and setting the EAS version to 14 in the settings. I also tried 2.5 with no difference.

I then installed the TBSync add-on, and from the settings menu clicked the "add EAS " addon, which I did. I added my hotmail (Outlook) account and it automatically connected and told me I needed to sync.

I clicked "Synchronise Now", after selecting the Public Holidays, Birthdays and Calendar calendars. All three synced with no errors, and the above behaviour was observed: All the events were scattered across the year wrongly.

I created a new birthday in Tbird and hit Sync, but despite the sync completing "correctly" (no errors in log), no event has appeared online.

I have checked for the event being scattered to 2022, 2023, 2024 and 2025, but despite it being a "Yearly" event, it doesn't appear (if the scattering is bidirectional it could have landed anywhere in a 4000-year window! :D )