Step on apron

Greetings. Have an issue with one the Airports I’m working on.
ULMM.
I’ve made new apron and making right now markings.
When I was checked it I found a huge “step” on apron!

How to get rid of it? Also when I’m loading without my project edit step dissapeared like nothing happen. I checked Apron propeties, markings, I can’t get it.
Tried to switch off roling cache. Still nothing.

UPD. Downloaded fully new project from World Hub Download Airport and this issue still there even with full default

Thanks in advance