monitor marking down all pool members at a time

Im having a strange issue. I observed that all the pool members are being marked down, at 4:00 am everyday in this bigip. But the same server when monitored from diff bigip is showing up at that point of time.

Need help on this if it is any bug. I have checked all the logs and found no other logs at that point of time. Checked for any daemons being down at that time and observe that all are running fine without any issues from last 30 days atleast.

My device: 3400 ltm

TMOS: 10.2.3 build 123.10