I nearly fell off my seat when I found this out today, but I have gotten this confirmed by technical support and wanted to share this with everyone/ask if anyone else was aware of this? I am going to start off by saying this is a BIG deal
So for the non-believers of the title, I have a screen shot below of a custom Account object SFDC field in my Marketo instance. You will notice the date says April 14th, which means that on April 14th, this data value changed in SFDC and a change data value log on April 14th (or later if you have a syncing backlog) should appear in your activity log.
Except, we DO NOT have that log...
This record was created on 3/30/16, so that is not the issue either. What I was told by support is below:
Mike called because the field most recent demo set date was not showing up in activity logs. This is due to some backend Marketo logic to not show these updates on records because this would bog down the system. The data still comes through.
Support added that these data value changes will get logged randomly, but not for all accounts or contacts and there is no formula as to how it happens. To give you an idea why this affects me, we do a lot of account level reporting in Marketo with progression statuses based on account fields and listening to data value changes on the account object.
So I wish there was clear documentation on this and this is certainly a big pain for a lot of B2B customers who use the Account object to a high degree for tracking. This can be fixed by creating contact fields that mirror our account fields, but that is going to require a decent amount of work.