Can't sign in to iMessage on iMac
For a few years, I've been using iMessage without problem on my iPhone, iMac and macBook. But recently I've been receiving a few notifications on one or more devices about associating my phone number with my iMessage account (I think) and today, I can't sign into iMessage on my iMac. Or, at least, I can sign in for a few seconds before I'm signed out again. Any ideas, please?