Ah, you're right, you did say that.
I see you're using the Media Foundation AMD VCE. I'm not overly familiar with AMD hardware or encoders, so I'm not sure about anything I'm going to say from here on out. Anyone with more knowledge on this subject is welcome to chime in and correct me.
From what I have read, the AMD R9 390 uses GCN 1.1 and VCE 2.0, which only supports up to 1920x1080@30fps for encoding.* Again, I'm not 100% sure on this, and it's been hard for me to find any reliable information on the subject. Try reducing your FPS to 30, and try recording again.
As an aside, the upcoming
AMD Advanced Media Framework Encoder Plugin for OBS Studio might interest you. However, it is still somewhat experimental at this point. Reading your log more closely, it seems you might have had it installed at one time?
* Some places I've read say 1920x1200. Some places say 1920x1080. Some places say 1080p@87f. Some places say 1080p@30f. Most places don't say anything at all.