Microsoft, you are disappointing me more and more with.
"We have not received reports from other users" is not a reason to not treat an issue as a bug. Any bug starts with 1 report. Also, how many users actually do report bugs? No, seriously, think about it. Most users will just treat this as an annoyance, and they will not contact support, because they know you won't be helping them, and you will just be deflecting, and deflecting, and deflecting again. A bug is a bug even if it is reported just by 1 person.
The "we were not able to reproduce" is also not an excuse to not go with this to the devs and continuously waste my time on actions that have nothing to do with the issue. I repeat myself again: I am a tech support, like you, if I have just 1 setup where the issue is easily replicable, and I can't replicate it in other setup, I will still go to the devs with a bug. Yes, it obviously won't be fixed at high priority for obvious reasons, that understandable. But they do know the code. If they watch the video and look at the code, read the assumptions I've shared - they may get an idea what is happening and why.
Even if they don't - they have a great opportunity to coordinate with me and provide me some debug build or whatever that will allow them to monitor what is happening during startup and analyze the logs then. Or maybe they already know about this even. I would not be surprised by that at all.
Either way, STOP DEFLECTING!