In short:
CADViewer causes Nextcloud Office to misaligne from the top, and when the share dialog is opened in NC Office, the share dialog opens behind Nextcloud Office. Please visite the original issue regarding screenshots.
This behavior also depends on which desktop resolution is used.
After disabling CADViewer NC Office works as expected again.
Originally this issue/thread on richdocuments was opened: https://github.com/nextcloud/richdocuments/issues/3199
In short: CADViewer causes Nextcloud Office to misaligne from the top, and when the share dialog is opened in NC Office, the share dialog opens behind Nextcloud Office. Please visite the original issue regarding screenshots. This behavior also depends on which desktop resolution is used. After disabling CADViewer NC Office works as expected again.