Scoring stops?

The other day I posted about my score stopping for no clear reason, never going up and only going down when I died. Some of the answers were that I passed the par time, another person said that was just multipliers but passing double the par time would stop the score.

But I just started over on Crow's Nest (MCC, Heroic) and the same thing happened. I set a timer and I had only been playing for 4-5 minutes when my scoring stopped increasing.

Can this be related to skulls? I only have a few on, but nothing that should be causing this much issue