Sync Sharepoint folders containing dots in their names won't work

I just got my Nextcloud installation running and it works like a charm… Almost.

I integrate my old Sharepoint as external storage to copy all my files over to Nextcloud. After checking some of the copied folders for consistency I noticed, that the Sharepoint integration doesn’t show or sync any folders which contain a dot anywhere in their name. As I have thousands of such folders in my old storage, I would very much like to avoid renaming them. Is there any filter for example, that’s influencing this behavior or is it just a bug or feature limitation of some kind?

Thanks for your help

Nextcloud 20.0.4
Debian 10.7
MariaDB 10.3.27
Nginx 1.14.2
PHP 7.3.19