Question / Help Replay buffer recording only ~30 seconds regardless of settings

[Shampooh]

Title pretty much says it all. I followed the advice in this thread but it hasn't remedied the situation at all. I have 64 gb of RAM and it's seeing barely any use while the buffer is active, so I'm rather stumped to what the issue actually is.
Here is a log where I attempt to save an MP4 and two MKV's, all coming out to about 20-30 seconds: https://hastebin.com/hukadeyoti.http