Synchronised coasters not working

[HarryLUFC]

I've built this 4 way duel coaster that works well, has great stats and all have similar ride times. The issue is that when one ride breaks down, they all stop and dont run anymore.

I originally had all 4 exit stations alongside each other and had the issue then, and have now put them in pairs and this doesnt help.

There is probably an easy fix to this but im not familiar too much with the ins and out's out of it.

The park file is below as well.

 

Forest Heights.zip