Signals & Track Service Stuck - Stop Waiting Yard Manager Permission

I'm building a route and one service starts within a yard, but it does not move at all. When simulating I see the following messages:

Code:

TS2Dispatcher: Find path for 3S50 took 0.006 seconds
TS2Dispatcher: Setting junction {8F8A8DEA-4027-4FF8-7708-A2AD8B3E93BA} to state 1 for services 3S50 due to initial section acquisition
TS2Dispatcher: Setting junction {46BD8609-43B5-744C-F2D0-8A952908D360} to state 0 for services 3S50 due to initial section acquisition
TS2Dispatcher: Setting junction {C35CDD74-48A9-9097-CD79-E0B24EE5F72D} to state 0 for services 3S50 due to initial section acquisition
TS2Dispatcher: Setting junction {F8734F31-47F7-9DC8-F087-309FC7AD6D51} to state 0 for services 3S50 due to initial section acquisition
TS2Dispatcher: Setting junction {38233782-46EF-A88D-49E0-81B8AB9E835E} to state 0 for services 3S50 due to initial section acquisition
TS2Dispatcher: Setting junction {215F8A65-4FDC-D97C-E374-20A042DF0F40} to state 0 for services 3S50 due to initial section acquisition

So far so good, until:

Code:

TS2Dispatcher: Unable to acquire initial track section (0) for 3S50 acquired previously by 3S50
TS2Dispatcher: Unable to acquire initial track section (0) for 3S50 acquired previously by 3S50
TS2Dispatcher: Unable to acquire initial track section (0) for 3S50 acquired previously by 3S50
TS2Dispatcher: Unable to acquire initial track section (0) for 3S50 acquired previously by 3S50
TS2Dispatcher: Unable to acquire initial track section (0) for 3S50 acquired previously by 3S50

Then the AI service is stuck waiting:

Code:

LogTSWAI: TS2AIController::LogTargetConditionStatus: [TOD] +05:34:00.050, [TargetSpeedCondition] Stop Waiting Yard Manager Permission, [Service] 3S50, [Location] Lat: 53.52906, Lon: -2.61598, [CurrentVelocity] 0.00m/s
TS2Dispatcher: No active route requests for service 3S50
TS2YardManager: Status for service 3S50: Failed Already Locked Locked By Services:
LogTSWAI: AI has been stopped for 120.102730s

The route is clearly set up and will work (with manual points changes)


But its stuck in the yard for the whole timetable.

 

I've figured it out thanks to some help from folks - the yard manager does not like any signals inside a yard, except yard-exit signals. It's better to imagine that the yard manager knows nothing about signals and defers yard-exits to the dispatcher AI. I removed internal shunt signals and only had yard entry/exits on the edges of the yard.

Hopefully my revelation helps others.