Layer above video making video disappear

SOLVED: I reduced the size of the image and it now seems to be working. Original size was 4000px length, reduced to 1920px.

I have a strange issue occuring:

- Top layer is a JPG image which covers a section of the screen

- Bottom layer is the video (.MFX file)

- Video not displaying, although audio is working

Then...

- If I delete the image and then UNDO that delete, both the image and video layers display

- If I restart Premiere, the issue returns

I've tried:

- Changing the preview resolution

- Changing rendered to Mercury Playback Engine Software Only

- Using different image file formats

Computer info:

Premiere Pro Version: 14.0

Windows 10

Processor: i7-6700K CPU @4.00GHz
Installed RAM: 32GB