I actually have a possibly helpful update. When I tried to kill the process using MultiMC's latest version, it actually reported the process number that it couldn't kill. The error says: "Failed to kill process 5080 (error 5: access is denied)" I'm not sure if the process number is unique to me, or if it can be used to trace the bug. We also know from that error that it's an access issue. So... progress?
I actually have a possibly helpful update. When I tried to kill the process using MultiMC's latest version, it actually reported the process number that it couldn't kill. The error says: "Failed to kill process 5080 (error 5: access is denied)" I'm not sure if the process number is unique to me, or if it can be used to trace the bug. We also know from that error that it's an access issue. So... progress?