This issue occurs because the obsolete MailboxDeliveryAvailability health management probe, monitor, and responder that are defined on Microsoft Exchange Health Manager service startup are still enabled by default. Therefore, the auto-replaced MailboxDeliveryAvailabilityAggregation probe, monitor, and responder are not fully implemented.
To work around this issue, use one of the following methods:
Run the following global monitoring override to disable the MailboxTransport\MailboxDeliveryAvailability health monitor probe:
Add-GlobalMonitoringOverride -Identity "MailboxTransport\MailboxDeliveryAvailability" -ItemType Probe -PropertyName Enabled -PropertyValue 0 –ApplyVersion "15.00.xxxx.xxx"
Restart the Exchange Health Manager service (MSExchangeHMWorker.exe) to release the handles in the Lsass.exe process.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.