Android nextcloud client doesn't 'see' files

I bought a new Tablet and am struggling to sync my files between the new Android Tablet and my windows Desktops. This far I’ve only been using Windows and had my files encrypted with cryptomator.
This didn’t work out well on my android Tablet.
So actually I’m trying to sync the files via nextcloud and encrypt them with encfs. So I installed EDS Lite, created a container within a folder inside the synced nextcloud folder.
My problem is, that nextcloud doesn’t ‘see’ the encfs files. It shows the folder as empty and nothing is synced towards the nextcloud server. Checking the very same folder with another filemanager (e.g. Total Commander) shows me two files “.eds” and “.encfs6.xml”.

Nextcloud shows the same behaviour, when I create a file in the opened encfs-container: I can see the (encrypted) file in the filemanager Total Commander but I can’t see it in the nextcloud app, and therefore it is not synced.

This way I will not be able to create files on the tablet, which is very important for me, for the intended use of the tablet.

It seems to me, that the android nextcloud app, doesn’t recognize files, created with a third party app (e.g. MS Word, Filemanager, EDS Lite etc.)

I would be very glad if someone could help me, sync files, I created on the Tablet.
Thanks in advance.