Using Outlook for Android in business environments for email and scheduling
The reason installing from the Samsung store may have helped is that the problem began in a somewhat recent release of Outlook from a few months ago. Samsung store version is old enough that it doesn't have that problem.
The current version of the Outlook app in the Samsung store is from June 2024, version 4.2422.0. It will not have any of the security updates and other fixes that may have been added to the Outlook app since then. I would not run an older version of the app if it is not necessary. Just not worth the risk, and is not necessary, as the current release from the Google Play store works fine.
Samsung store version of the app:
The current version of the app in the Google Play store is 4.2435.1, and using that version both email and calendar sync are working on the watch. Strongly suggest everyone get the play store version and not use old versions of the app from the Samsung store.
Play Store version of the app: