LG OLED 55BX white flash

Hello everyone, I need some help,
I just bought a new LG BX, and while watching stuff on my PC (RX 480) via HDMI it keeps appearing, really fast, a white screen. I tried setting the resolution to 1080p and it seems that it fixed it (at least for the time I tried), but obviously I want to use this tv at it's full potencial, 4k. Also, I only found this issue while using the PC. I also used it with the PS4, without issues.

I also tried disabling Freesync but with no luck.
I manage to take a video of the flash and you can find it in this post, also with a screenshot of the video.

Video of the flash (arround sexond 21~22): https://youtu.be/AF1fbdarFK0

Screenshot of the issue from the video: https://ibb.co/wsY8pLG

Does anyone had this problem before? Can someone help?

Thanks!