Removed audio source selected (and not found) when not logged in

Steps:

1. I added a YouTube audio to my score https://musescore.com/bluebirch/you-don-t-have-to-leave
2. I updated the audio track by deleting the old YouTube video and adding a new one.
3. I added the new audio source to my score and marked it as default.
4. I deleted the old audio source from my score.

Now, when LOGGED IN, the correct audio source is selected. Checking audio sources shows what I expected, that is, three audio source of which one is the updated YouTube audio source.

When NOT LOGGED IN, playback cannot be done because of a Youtube error "this video had been removed by the user". Obviously, the old audio source that I thought I had removed is selected. Checking audio sources, it shows FOUR sources of which one is the old, removed YouTube audio source which is selected by default, and one is the correct, updated YouTube audio source which is NOT selected by default.

Weird, isn't it?

I have tried logging in, logging out, restarting browser, clearing cookies and all that stuff, but the problem persists: when logged in, it works. When not logged in, it does not.