The issue was hit in the following scenario:

1. The router (DUT) receives syncronization (via PTP and SyncE) from the upstream router. The DUT router sends ESMC messages from the master ports with the quality PRC.
2. The upstream router was upgraded so the upstream router was offline for some time during the upgrade.
3. During the upstream router upgrade the DUT stopped receiving PTP/SyncE synchronization so the DUT router starts sending ESMC messages with the quality ECC1.
4. After the upstream router was back online, the DUT router became again in synch with the upstream router. However the DUT router continues sending ESMC messages with the quality ECC1 via master ports in stead of PRC.

The root cause has not been found as the issue is not reproducible and happened only once in the production network. The incorrect state can be cleared by flapping each master interface.