In reply to cgales:
I believe a scenario with more than 1 lock is not useful in general. Which one should have the priority?. The UVM does not specify this. I have modified the exmple slightly and it worked as expected. The grab sequence is executed first, because it appears in the arbitration fifo at the head. Afterwards the other sequences are executed starting with the lock sequence. See here:
I used the arbitration mode UVM_SEQ_ARB_STRICT_RANDOM.