After tinkering around with turning the new menu flag on and back off (through bloxstrap), I found that the bug had returned from my last report that was previously closed. The previous post will be included for more information to provide.
It was originally marked as a solution since I had it fixed at the time, but it seems it has come back because of the new menu.
Updated Info:
It seems that trying to report someone by using the report button in the playerlist causes the menu to turn up blank. I have not tested this in my previous bug report on this, but I hope this helps.
There are currently no flags apart from using a flag to turn the FPS cap from 60 to 120. This doesn’t change the behaviour of the reports menu.
It is still happening on my phone as well. I assume my phone always had the issue since my last report.
I can confirm it isn’t Bloxstrap due to it also occurring on my phone (which is unable to use Bloxstrap, but even then, Bloxstrap doesn’t alter the client itself).
A private message is associated with this bug report