sillz - Thanks for posting your question on the forum!
Would you be able to post your configuration on the forum? Please remember to remove any sensitive information. I would also be interested in looking at the event-history.
Although you mentioned that NTP is disabled, one note I did want to make was that the NTP issue that could cause these messages is actually resolved in 18.02.03.
Please do not hesitate in letting us know if you have any questions.
We updated to 18.2, and this resolved the problem.
Systems Engineer - Network
Information Technology Department