This has been going on for awhile with me, but when I try to remove a list that has been added by me, it often causes a lot of errors to the site. First it usually takes a long time removing, then usually send an error that either iCM is down or there is a 404 error. The list is occasionally removed, but sometimes I have to try again.
Similar experiences. The page that says it’s removing the list just stays there forever. After a while I close the page. Most of the time it actually removed the list, but sometimes not. I don’t have errors afterwards.