Server side encryption does not work


I use Nextcloud at home. It was installed under Ubuntu 16.04 with Snap.
Then I created an admin account.
I installed the tool “Default encryption module” and then activated the server-side encryption in the Settings -> Security.

Now I have the problem that he does not accept the settings. He doesn’t ask for an encryption password.

There is always the message “Please activate server-side encryption in the administrator settings to be able to use the encryption module”.