Elliott,
Yes, I've had problems--very similar if not identical. After much investigation, I realized that any forwarded messages were not being delivered until the next morning, even though the log indicated that it was sent immedeately.
The reply from Marketo support was that there was a bug in the implementation. The problem I had was described here:
http://community.marketo.com/MarketoDiscussionDetail?id=90650000000PbQFAA0They claim the fix is not available until June at the earliest. I haven't received any notice that they've resolved this yet, so I suspect we're still waiting.
Thanks for your patience with this.
Engineering looked into this, and found an issue with the implementation in regards to this feature. They are working on a fix, but are speculating that it can take some time - the June release would be the earliest.
If anything changes, I will let you know!
Regards,
Jim
Marketo Support