Whenever I try watching a replay to submit a run, it never shows the run, it always shows one singular I piece with more on the side. Does anyone else get this or am I the only one?

Maybe click the « load » button on the bottom of the board?

That's what I did? That's why this forum is a thing?

Could you link a specific replay that isn't working for you? And do you have any scripts running as you play? There has been rumors that real block can mess with the replay system.

https://jstris.jezevec10.com/replay/15904002 My 40L PB I got last night, for example.

Works perfectly fine for me.

Or maybe try to uncheck the WebGL setting on the + tab in your game settings

Try doing what Sausty mentioned, and check if your runs still can't be replayed after that. Also: are you using any additional scripts or plugins during your game? They may have a great impact on this situation.