As was mentioned, “door ramps” or an accumulation of semi hard gunk builds up on the door tracks where door travel stops. Eventually this “ramp” causes the hall door or car door to initially make up, but then drift off the limit or lift/separate the lock contacts enough to loose DL input or DG, DCL inputs. Sanding the tracks regularly avoids this all to common issue.
Also check:
Spring tension on the reel closer.
Door operator belt for wear when on the door motor sheave
as this will cause DCL failure and failure at “squeeze” when initiating a run.
