That was in the digitally-controlled analog equalizer I worked on (and still AM working on) with my dad, we kept sending something through the SPI line that was consistently sending clown vomit and corrupted data to the display and as a result my whole code was hanging and bootlooping like crazy.

The fix? No idea! Because I had (and still don't have) ANY step-based debugging, all I could do is try multiple ideas and see if one of them would stick. That ended up being the solution.

I still have a video of this issue, I just need to find it. I will post it here when I have it.