Salesforce Custom Object Error Message
We recently created a new SFDC custom object that maps our leads/contacts to their product trial user account information. I've had success with Salesforce custom objects in the past, but this time around I'm receiving an error that the object was modified in CRM since the sync was last enabled. See below:

Please note: nobody is is modifying this custom object in SFDC so this error is completely unwarranted.
Now, I've tried a number of ways to troubleshoot - I've refreshed schema, disabled and enabled sync (multiple times), logged in and out of Marketo - and nothing seems to work. I've also submitted a support ticket but Marketo Support doesn't have any explanation as of yet.
Anyone have any theories or past experiences they can share to help me solve this issue? Thanks in advance!