Only recently within my AE comp, I have had an odd shaped red glitch appear. It is not linked or attached to any layer within my composition, it just appears at random points. (SEE ATTACHMENT)
ALSO - it appears when I render AND appears in a NEW project with no layers or any assets within my comp.
Lastly, my work colleague does not have this issue.
My AE is fully updated as well.
Purge the caches: Edit > Purge > All...
Perfect! Thanks Todd.