No, this is definitely not expected behavior, we're not currently aware of this or similar issues. Do you use the collector service in your setup?
When this happens and you look at the heartbeat status, is the timestamp associated with each line item up to date, or outdated? Is the ping status accurate? I realize that you may not have this info, but knowing this would be helpful the next time it happens.
Please also set the debug level on the "Heartbeat" dialog to "High" and save the configuration. The next time this happens, please immediately copy the files from %systemroot%\syswow64\eventsentry\logs\eventsentry_hb_svc*.log to a temporary folder in case we need to review them.