I use Joplin 2.7.13 on MacOS Catalina (the previous version of Joplin also had this error). I also use Joplin on an Android phone, and it has the same yellow banner.
I saw on the forum that other people have had this issue, but there were no resolutions (except for hiding it with CSS, which I don't want to do, I want it gone).
When I click on "Set the password", it takes me to the encryption page, but there is no area to enter the password!
I use Joplin Cloud for syncing. I also have a shared notebook with my partner, and I can't access the links he adds to the notes (there is an hourglass next to the link), I'm wondering if this is due to the missing password?
Yes, they are all in sync. I just tried to press "synchronise" (again) – no change. Joplin is asking me to set the password (the yellow banner on all devices), but there is no place to set this up.
What do you see under Encryption Config? Is Master Password: Loaded? If so, you’ve probably setup more than one key and are using different keys on different devices.
On the desktop, hide all but one key, and note the ID. Then make sure you use the same key on each device.