Adding hidden files for sync

I am using the latest Nextcloud Desktop Linux Client. How can I select hidden/dot files from the desktop client?

When I try to add them they don’t show so I can’t select them… Currently I have to add them manually through the web app.
Thank you.

Similar problem, but on Win 8.1, newest Nc client, 3.3.0, but persisted on 3.2.1.
Nc v. 21.0.3
shared server Ubuntu.

What I need to do is to sync all .~lock.* files. Yes, to sync them.
So, in “Edit ignored files” I have ticked “Sync hidden files”. All the rest is by default.
Each sync folder has no files to be ignored. Just blank window.

What and where should I change the setting to have these files synced?

Will be very grateful for any help,