Hello,
I currently have an EX-4600 that has 3 active subnets configured out it with an export policy that advertises all directly connected routes. The routes are advertised to it's neighbors one of which is an EX-4550 and the other a Cisco Router. For some reason after about 24-48 hours the EX-4600 stops advertising it's directly connected routes. The neighbor state between the EX4600 and EX4550 is in a full state, but the neighbor state between the EX-4600 and Cisco router is in Exchange mode. The only way to get things back running is to clear ospf neighbor on the EX-4600.