You are confusing the 551 and 552 again.
The 551 is the empty one starting from MLW depot
The 552 is the one who starts from RSCK (803).
The 20 permissief is for the 551. The problem of the 552 is that he's supposed to start (and so: leaving the block 803) at 8:00:00. However, he leaves at 7:56 and didn't change his number. Additionnally, he didn't get the path to 215 and stays stuck at RCS