Playback and export showing frozen, glitched frames

When I playback my video edit, it (pic 1) shows frozen frames and premiere pro will export the same fuzz into a video (export settings in pic 2). The audio is still continuous but the video freezes for a second and shows glitches then clears itself after a second or two. This happens in some parts of the video, but the majority of the video is fine. 

I made the editing timebase to 60fps from 23.976 fps (original source), but when I started a new project and loaded the source video with the original settings untouched, this fuzz thing still shows up at random points (sequence settings- pic 3). And even if I don't add any edits (I basically only use text and Motion- Position and Scale), the freezing still occurs.

The source video (MP4) plays fine outside of Premiere pro and has no glitches. Premiere pro itself is not laggy; it runs smoothly at full resolution playback and the same problem occurs at 1/4.

I've tried rendering it, restarting the program, reinstalling adobe, deleting media file caches, and restarting my computer, etc. but I can't figure it out.

Is there anything I can do and is there a reason why it's like this? Maybe it's my computer or adobe itself? Or something I did to the clips?

Thanks 🙂

Intel (R) Core i7- 4930K CPU @ 3.40GHz

RAM 32.0 GB

64-bit OS

Premiere Pro 2020 version 14.7

Radeon RX 580 4GB