[resolved, kind of] stumped with turntables, why won't turn?

I can drive an engine onto and off a turntable on my route, but can't turn the turntable.
I can drive onto the turntable even if it's not aligned.
screenshots show two different turntables; all nine turntables on my route are failing like this.
Any ideas what would cause that?
I can drive onto the turntable even if it's not aligned.
screenshots show two different turntables; all nine turntables on my route are failing like this.
Any ideas what would cause that?