chronyd sometimes stays at stratum 10 after boot

Issue

On some of of our RHEL7 systems we have troubles with chronyd at boot time. It stays at stratum 10 and does not synchronize the system clock. All peers show as unreachable. Other servers in the same network zone do not have this problem. A restart of chronyd fixes this issue. There might be a potential race condition during service startup, e.g. chronyd starting before network is up. Logs confirm that this is the case. However, other servers which do not show the same behavior have similar logs and still chronyd seems to manage to catch up. Is there a bug in the startup order and/or in the chronyd code which handles fallbacks/recovery from network problems.