Steps to reproduce:

1. Monitor a host with a proxy in between, get some active and passive items, see that after a while green icon gets grey because of active checks seem not working. active icon configured is only the agent log on all of the hosts, but it seems that it is updated not frquently because there is not so much update in the log.
2. Problem seems to happen also with proxy agent itself, so there is monitored also the proxy log as this is updated frquently, but also not showing green icon

Result:
See screenshot...