I have set up automatic upload, this works correctly, as well as nextcloud client + icon uploads everything correctly. Hence the problem is not in the NC16 server side.
When I open gallery or audio app and press share chose nextcloud it flashses only short message “file copy from pricate storage” and nothing happens now file is put into upload queue. I have tried to upload the same file from inside nextcloud android app and it is successful.
Hence the problem is sharing api side.
The issue has already been reported:
Nextcloud 16 has already declared as being “End Of Live” in 04/2020!! You should update your installation asap to a supported version 18 - 20.
No it is not server issue, API works correctly within nextcloud application but when sharing api is in use, there is not even connection attempt towards server. It is not wise to update from NC16, I know the code quite well and do not need new troubles at the moment. The problem resides in android new version 3.14.1