When clicking on "Add Transaction", I'm not able to choose the date. The dates have disappeared.
Screenshots

Desktop:
I can confirm this, has been happening for me for a few days. Disabling the toolkit fixes the date picker
Also experiencing this issue. I have been disabling the toolkit when needed but that isn't a sustainable solution.
It seems to be related to the calendar first day feature. When I turn it back to the default of Sunday the days are shown again.
It seems to be related to the calendar first day feature. When I turn it back to the default of Sunday the days are shown again.
Also seeing the same error, If you chose Monday no dates are not visible, if you chose Sunday (default) the days are visible
Duplicate of #2175
Closing this in favor of #2175, we'll have a fix in the next release.
Most helpful comment
It seems to be related to the calendar first day feature. When I turn it back to the default of Sunday the days are shown again.
https://github.com/toolkit-for-ynab/toolkit-for-ynab/tree/master/src/extension/features/accounts/calendar-first-day