I don't have much advice to offer when it comes to video. While I do use JRiver to watch movies, I do the absolute bare minimum… That is, I hit play and I watch the movie. I don't mess with MadVR, or JRVR, or frame rates, or aspect ratio, or any of the multitude of video tweaks you can make, as I really just don't care. That said, I can understand your frustration with long-standing bugs and fiddling with things that you feel you shouldn't have to...
however…
I would say the chances of finding another media player where developers directly engage with users to try and solve issues are virtually zero. For that to work however, users must be explicit in describing all that may contribute to the issue, such as your computing/network environment, what was happening exactly at that moment (the action taken and any operations that may have also been running), yada yada yada. If the error is clearly repeatable, perhaps try turning settings you suspect may affect it on and off and see if that "fixes it". To state the obvious, the more information the developers have from you the more likely it is they can zero in on the solution.
And of course, there is always the omnipresent antivirus configuration bogeyman. If you're using a third-party antivirus, don't, and when using Windows defender, be sure it is configured per this thread:
https://yabb.jriver.com/interact/index.php/topic,86096.0.html