We have had the same issues. It's very "hit or miss" with no rhyme or reason to it. We have leads within a company that sync fine, while others within the same company, with no differences as to preferences, do not.
By any chance, have you recently added any new custom fields to your sync? This is a hypothesis of mine that I have not yet been able to prove. It's super difficult to nail down the cause because it seems to be intermittent, but I have seen this kind of behavior before with 2011.
We have not. We've opened a case for this, but Marketo has not been very responsive. Fairly disappointed in their handling.
Ah well, so much for that theory.
If you're having trouble getting a response, we do have an escalations email address that goes to the support management team: email@example.com
Yes, thank you. I sent one first thing this morning and have not gotten any response from them, either. About 2 hours ago. Is there not a number we can call for support? I'm running out of time here.