Exchange stops data collection due to query Credentails time out. Beloow error is logged in the agent log:
java.util.concurrent.TimeoutException: Time out when query AD / EXC credentials.
Defect ID EXC-913 has been submitted to Developemt for a fix in a future Release.
As a possible workaround, try restarting Foglight Agent Manager (FglAM) that is hosting the EXC agents.