I am using Roundcube version 1.5.7 and installed the Mailvelope browser plugin (Firefox 127.0 on Windows), as recommended in the Roundcube settings. "Use Mailvelope main keyring" is checked, the domain + API are whitelisted in the plugin settings. I can send emails with encryption/signature and open them in other email clients.
I cannot figure out, however, how to decrypt/verify the message directly in Roundcube. The message body shows as "This is an encrypted message and can not be displayed. Sorry!" and the encrypted message is presented as a file that I can only download. I don't see how Mailvelope could grab the encrypted part, let me use a private key and show the unencrypted content. I assume that this is possible, otherwise the integration wouldn't make much sense.
(https://i.postimg.cc/Y0VY8HSr/roundcube.png)
Am I missing any setting or installation step to make Roundcube work with Mailvelope? Thanks for your help!
EDIT: It seems that it is working in Chrome.