I wonder if there are new power management settings and Edge may be putting the tab to sleep or something. I'll put it on the bench and see if I can reproduce and get back with you.
For now, try scheduling the same test using Chrome or Firefox and see if this resolves the issue.
If there are new settings I may be able to work around them.
Sorry for the extremely delayed response. I got your message right away and 10 minutes after you sent it I started scheduling some tests and investigating but wasn't able to reproduce the issue (but wasn't using Edge). I had it scheduled out for a while and then by the time it finished forgot to update this thread. My bad. -- Again, I'll give it a try using Edge, may provide more info. Pretty certain it's not an issue effecting large numbers of users.