Online agents aren’t appearing online in Headquarters

Online agents aren’t appearing online in Headquarters

We’re having an issue with agents setting their status to Online, and it usually sticks for a few minutes, sometimes a couple hours, but suddenly the round robin assignment stops assigning tickets.  When this happens, I check the Headquarters page and agents are showing offline there, even when their status is still showing online on the top right.

It’s possible that this is happening when someone goes idle for a few minutes (although the idle timer is set to 1 hour), but even if it is that, it doesn’t appear online again for the rest of the day.

I’ve tried setting myself to offline and back to online when I notice this, but it’s not changing anything.  It’s happening with all agents.

Any suggestions?  Thanks!