Continuous Acquisition Date "Sync Lead Updates to SFDC" Activities

Hey Everyone,

I'm curious to get your input on a strange potential bug that I've come across in a Marketo environment. Earlier this week, in the process of identifying the cause of sync latency, I noticed quite a few "Sync Lead Updates to SFDC" activities with no apparent trigger.  The details on those activities appear to show Marketo consistently re-syncing the Acquisition Date value to SFDC, across thousands of leads, yet the Acquisition Date remains the same each time (See Screenshot Below).

We put together the following test, in an attempt to verify the bug:

1. Created lead in Marketo and synced to SFDC - acquisition date 1/25
2. Changed acquisition date to 1/26 in SFDC @4:00 PM on 1/25
3. New value did not sync back to Marketo
4. @3:58 AM on 1/26 - Marketo logged a "Sync Lead Update to SFDC" activity, which overwrote the SFDC 1/26 value w/Marketo's 1/25

Has anyone experienced this issue, or any similar?

We have two theories:

1. There's an issue in SFDC that is not writing a sys-mod date to the MKTO71_AcquisitionDate__C field and is causing Marketo to perceive the need to update this field each sync cycle
2. In this SFDC instance, the MKTO71_AcquisitionDate__C field is a date field, where as Marketo is datetime. There could be a translation issue between the two field types.