Pegging C Drive with .tmp file on create .mkv FROM backup

[jono55]

So I started by making full backups of the Blu-Ray disc (with MakeMKV "backup" feature).
The .m2ts files made by the backup process play just fine on my computer.
However, when I try to THEN (after backup) use MakeMKV to create an MKV file of the main video on the backup, it absolutely PEGS the C: drive while reading the original .M2TS file and WRITING a .tmp file (see the attached screenshot).
You'll notice that the Source drive is "D:" and the output drive is "F:" (not the C: drive...)
I'm at a loss it's weird. And only happens on certain backups... other backups seemingly write straight to the output folder without first writing to the C:\Users\xxxuser\AppData\Local\Temp\MakeMKV-xxxx-x.tmp file first.


The issue is that it never finishes... just keeps churning for HOURS.
Anyone have experience with this?