It appears that most of my ramp agents got stuck at the bus stop at the public transport parking. Despite my hired plm 140 agents, it appears there is a maximum number of jobs that will be fullfilled (about 32).
I have tried to fire all ramp agents and rehire them. It only got worse, now only one task is fullfilled. Somewhere, somehow, I think there is a bug in their task pick up.
Bug report: ACEO-28915.