The customer changed OSPF interface-type from p2p to p2mp in Juniper MX core routers, which caused OSPF neighbors (hundreds of MikroTik edge routers) stuck in ex-start status.

The OSPF neighborhood among Juniper MX routers were fine.

Based on the troubleshooting, JTAC found many LSA with age 3600, it seemed abnormal.

Execute command - clear ospf database all - in the core routers reset OSPF database but it did not resolve the issue.

The customer wait till the mid-night, and try to deactivate/activate OSPF configuration in the initial MX router, which resolve the problem.

JTAC did the lab test based on the customer configuration, but we did not find any issue in JTAC ultralab. JTAC team does not have MikroTik edge routers.