Interupts (Station full/empty) not working?

[AutomatedPantaloons]

Likely some foolish mistake I'm making but I can't seem to make the station is full/empty or destination is full interrupts work.

Basic systems, iron mine is visited > on leaving evaluates if iron drop off is available > if unavailable divert to secondary drop off.

I have tried this two ways, one was to have a basic Iron Mine > Iron Dropoff route. I then added an interrupt that said if station is full/destination unavailable divert to Secondary Iron Dropoff.

Re-evaluated my approach and instead just added twin interrupts that lead to both iron dropoffs but with the condition station must be empty (the theory being only the interrupt for the empty station will trigger). So the train should hit the mine, fill up, evaluated conditions and choose the first best option (first interupt that isnot full).

I have found it simply selects the first interupt even if i have a train sitting there occupying that station.

I must be misusing the various destination available/station is full or not full logic but i am unsure how? I am taking into account that rules are evaluating as soon as the mines cargo is full triggers and this doesn't seem to be the problem?..