Configure Windows Defender in what particular manner? Specifically, change what? How?
Malwarebytes Anti-exploit is remarkably non-buggy. The times in the past when Anti-exploit has stopped something (false alarms cause by MS Word macros - long ago) it had a pop-up that said it'd blocked whatever.
I saw nothing like that when MC 28 and MC 29 crashed. Just, "poof" and it's gone, no explanation. I restarted multiple times, first trying MC29 over and over, then restarted a few more times trying MC28. Poof. Then for variety, I tried VLC player and it worked great.
According to the Windows Update history on my machine, the only things updated on 4/12/22 were Windows Updates, not the virus definitions. I read the changelogs for the updates; there were security fixes, among other things. It was a hodgepodge of stuff, like all MS updates.
So like I said before, particularly because of the timing - happening directly after the Windows Update was installed, it's hard to believe Windows Update was NOT the cause. In which case, as the updates roll out to other MC users, I rather suspect more people will be affected - then hopefully you'll figure out the problem and update JRiver.
I did a system restore to April 4, and everything is just hunky dory. I turned off Windows Update on all my machines, so I won't be experimenting with turning off the anti-exploit or whatever.
I do hope you figure out what the problem is and fix it so I can turn Windows Update back on. I don't like running un-updated.