Mhhh, I'm extremely disappointed. Me too I'm using a RAM DISK as a D: drive (with Imdisk) and I have pointed \TEMP to it. It's the very first software that is misbehaving like that.
That Github tracking has been going on for YEARS! It makes me openly wondering: Are they even taking this issue seriously? I'm not going to open a Github account just to complain. They're adult and should have dealt with that issue a looooooooooooong time ago.
I wonder why for every other software, it works just fine, and not the Arduino IDE? And no, I'm not going to get rid of the RAM DISK, nor pointing \TEMP to a real disk. That's NOT negotiable.
Seriously, they really need to put their act together. I don't know what they are attempting to do, but if they don't do anything fishy, therefore using regular system calls should work just fine... as it is the case for all the software installed on my PC that is dealing with the RAM DISK. Probably for most if not all of these softwares, they aren't even aware that they're using a RAM DISK. So there's absolutely NO excuse to have dragged this issue for YEARS!
So in the meantime, no Arduino. That's not negotiable in my case. However, I'm VERY disappointed, and I would have expected something more serious than that !