When I said converting, I just meant changing the extension.
That was it, cleaned out that folder and ran the ogg.miz. Mission loaded and played the sound. After playing the mission, the C:\Users\Ethan\AppData\Local\Temp\DCS.openbeta was still empty. But I'm extremely grateful for all your help, hopefully that solved the problem. Interestingly, it doesn't always have the issue, I'd go weeks with no problems playing mission then suddenly they'd lock up. There were a lot of files in that Temp file so maybe something was causing conflict.