Resolve 17.1.1 unable to export MP4 h264

Hi!
I've got an issue with rendering. I've finished coloring my 15min short film using newest version of Resolve Studio (17.1.1 build 9) with FilmConvert Nitrate 3.04 plugin. The files I'm working on are Lumix S1H's LongGOP 5952x3968 10bit 4:2:0. PC specs are Win10 Pro 20H2, Ryzen 5 3600, GTX970, 32GB DDR4.
Everything was perfectly fine, I've been exporting preview MP4's all the time with no issues, until for the final export I've cropped the timeline to 5290x3968 choosing the "scale full frame with crop" on both input scaling and output scaling - I was framing with 4:3 aspect ratio in mind. Export settings were MP4, h264.
Then suddenly GPU error started popping up all the time, stoping my export at around 10%-20% (no specific frame). I've tried multiple resolutions, to no effect.
Then I gave up and returned to my previous 5952x3968 resolution, just adding black bars and checking back the "scale to fit". To my surprise it also didn't help. I'm still unable to export my timeline.
Then I've cleared cache, then copied the timeline to the new project, then reinstalled both Resolve and the plugin mentioned above, still to no effect.

Here is the project file: https://drive.google.com/file/d/1Z43x42 ... sp=sharing

I've got no idea what to do, pls help.

I think you're going to struggle with a GTX 970. (I say that because I have one myself. It's...insufficient.)

Unfortunately, it's near impossible to get an RTX 3000 series card today.

Second that. What you could try is an export into DNxHR and then encoding into H.264 with Handbrake.
But why do you want such resolution after all? It’s not a standard for video.