Displayport monitor flickers when using HDMI adapter

[Statek]

I have two monitors that only have DisplayPort inputs that I need to power from computers with only a HDMI output. One of them works perfectly fine, the other keeps going back and forth between showing the image and then losing it, and both work fine with a direct DisplayPort connection. I have tried several hundred dollars worth of adapters and they all cause this issue.

There is an option on the OSD to show timings which is where these two monitors differ (along with the working monitor's AD board having newer firmware), though I'm not exactly sure what they're referring to, and trying to force eachothers timings (and a variety of different resolutions, refresh rates, clocks, etc) with CRU has made no difference or made things worse. It seems to flicker more frequently when being handled, which I could attribute to a damaged board, except we have hundreds with the same behavior. Both monitors/AD boards show up with identical settings in CRU.

Does anyone have any ideas on how to fix this? Best case, I'd be able to send a clear signal to this display with some CRU edits to eventually be driven by a Raspberry Pi, though hardware fixes or overpriced adapters may work as well (though I've tried all I could find).

Here's some more info, along with a video and pictures of the default CRU details and monitor timings:
1280x242 resolution (yes actually)
TX38D09VM0CAA panel/AD board
Video of the issue, maybe with some telltale artifacting of a timing issue? The artifacting on screen on/off seems to be more intense at the native resolution than anything else, though I can't draw any conclusions on the exact cause:
https://youtu.be/Uj7VDyua-kQ

[ToastyX]

Usually flicker like that is a signal quality problem, but I don't know why one monitor would handle it better than the other. Maybe there's a firmware bug with the older version.