OBS will not use GPU, regardless of settings

Sometime this week when I was constructing scenes, with no input from me I opened it to find that OBS was now lagging my entire computer. When opening Task Manager I found that it is now--I stress with nothing having changed--using 72% of my CPU.

I have already adjusted all of the settings and done all of the common steps recommended to fix this:

• Launched in Administrator Mode
• 30 FPS
• Windows Graphics Settings setting OBS to use GPU
• Output Settings setting Video Encoder as Hardware (AMD, H.264)
• Updating drivers
• Restarting

None of these steps even made so much of a single 0.1% dent in the CPU drain. Frankly I have done everything short of reinstalling the entire program or switching to Linux. I'm using a PC with only one GPU so there is no question about it using the wrong one.

We've tried loading identical elements on a friend's PC with identical filters, and on her PC with a less powerful GPU/CPU it works fine with OBS barely taking 3-5% of the CPU load when on mine disabling everything but the testing element still kept the CPU load somewhere around 20%--even if the files I'm using for the elements are a little beefy, this is certainly not a problem with the files just being too big.

Has anyone encountered this kind of thing before? Is there anything I've missed? A friend thinks it could be because I have an AMD GPU, but I've seen plenty of people here talk about having AMD GPUs without this happening to them. Any pointers greatly appreciated!