Hi,
- For the missing app issue, could you please help to confirm if the missing app only disappear from applist or tiles in start menu or even disappear under following path: C:/Program Files/WindowsApps
https://www.samlogic.net/articles/windows-8-windowsapps-folder.htm
2.As you mentioned this is new environment with workstations and servers, have you got a chance to check the image you've setup? If there is any issues related to the image preinstalled.
3.Could you please test in one PC by removing from Domain and log in with newly created local admin account or standard account?
4.From what I have found when running the mentioned command with elevated powershell(run as administrator), it supposed to Re-Register All Windows Apps for All Accounts
https://www.tenforums.com/tutorials/3175-reinstall-re-register-apps-windows-10-a.html
Please note: Information posted in the given link is hosted by a third party. Microsoft does not guarantee the accuracy and effectiveness of information.
Hope this helps and please help to accept as Answer if the response is useful.
Thanks,
Jenny