Are there any Data Value Changes to datetime fields between it and the most recent successful sync to dynamics? You could also use the activity log search to look for that particular date time string
We are having the exact same issue that started on 8/24. Marketo Support said it was something on our side, but we haven't made any changes. Have you received any response from them?
Btw, we installed the latest version of the MLM a few weeks ago, but the issue just started occurring. Since I saw that you're having the same issue, I just requested that they escalate the issue to Marketo Engineering.