I was testing the collaboration link for a future video, adding as many channels as possible as collaborators. I copied the link, saved the tab, and tried accepting the request on the other channels. Out of the 5 collaborators, 2 managed to accept the request without problems, 3 had problems (2 are resolved, but I don't know how), and 1 is still locked out.   
This last one is strange, considering I have more than 10 videos in collaboration with it, and every time I open the link on this one, two things are happening:

1. It briefly shows me the thumbnail of the video, but quickly switches to this image
2. YouTube sends me to the "something went wrong" page, saying that I should change the account I'm using. If I select the same channel to go back to YouTube Studio, the loop starts again

Everyone on YT and in the other posts says that I have to save, but even doing it 10 times doesn't change anything. I even tried removing and adding back the problematic account to the collaboration, but nothing has changed.

Some accounts are related to the same email, but the one which sends the collaboration and the one with problems aren't. As I said, in the past days I sent collaborations between 2 accounts related to the same email, without problems.

Am I the only one with this problem?

Thank you so much

Collaboration not working