Gameplay Timetable Sim - Stop Manual Couple

I've got a loco runaround in my Niddertalbahn Modern timetable but in the simulation the service gets stuck on:
LogTSWAI: TS2AIController::LogTargetConditionStatus: [TOD] +23:55:09.800, [TargetSpeedCondition] Stop Manual Couple, [Service] Stockheim Sidings Loco Run-Around, [Location] Lat: 50.32803, Lon: 9.00956, [CurrentVelocity] -0.00m/s, [OtherRailVehicle] RVM_HBK_DB_785pza_C_1, [OtherFormation] Stockheim Sidings Loco Run-Around_Uncpl0

The loco uncouples fine, and will enter the track to recouple without issue but then it won't actually couple to it. It isn't a major issue as it's the final instruction in the service and there are no following services but it would be nice to get it working correctly.

Has anyone had a similar error in the log and found the issue?

 

Are there any other lines about scripts being called (and failing) around the one that you've quoted?

 

This is the full set of text:
LogTSWAI: AI has been stopped for 120.102730s
LogTSWAI: TS2AIController::LogTargetConditionStatus: [TOD] +18:38:54.000, [TargetSpeedCondition] Stop Manual Couple, [Service] Stockheim Sidings Loco Run-Around, [Location] Lat: 50.32803, Lon: 9.00956, [CurrentVelocity] -0.00m/s, [OtherRailVehicle] RVM_HBK_DB_785pza_C_1, [OtherFormation] Stockheim Sidings Loco Run-Around_Uncpl0
TS2Dispatcher: No active route requests for service Stockheim Sidings Loco Run-Around

And this is how it's set up in the editor:

 

Coupling/uncoupling can sometimes be a bit buggy. You might want to experiment with adding a 'wait' instruction before and/or after the coupling instruction (this is a load/unload instruction where you untick both load and unload) or add a 'goto' instruction (with call on dependency) into the coupling block. I've had the exact same (copied) instruction malfunctioning where another instruction worked. It seems coupling and uncoupling is a type of instruction that is very fragile and prone to some kind of bug. I didn't find one solution that fixed all errors yet, but deleting a malfunctioning instruction and replacing it with a new one sometimes worked.