Cannot save E2E mnemonic on second desktop client

Nextcloud server: 19.0.4
Desktop client: 3.0.2 (Ubuntu) (also same with 3.0.3)

I am using e2ee successfully on my desktop pc and android phone.

Tried to setup another nextcloud desktop client on my laptop. The laptop client asks for the E2E passphrase on start and when I copy & paste the mnemonic from my main desktop to the laptop it does not accept the mnemonic.

I simply cannot save the value - the input dialog just stays open. I can cancel but then there is no mnemonic at all and the files cannot be decrypted.