MR Job stuck in ACCEPTED status without any progress in Fair Scheduler because there is no resource request for the AM. This happened when you configure yarn.scheduler.minimum-allocation-mb to zero.
The problem is in the code used by both Capacity Scheduler and Fair Scheduler. scheduler.increment-allocation-mb is a concept in FS, but not CS. So the common code in class RMAppManager passes the yarn.scheduler.minimum-allocation-mb as incremental one because there is no incremental one for CS when it tried to normalize the resource requests.