Really the issue is the fact that Marketo was not validating the fields prior to their most recent update to the the "fast import" process. Many fields may have character limits that had never been validated. For instance I am unable to load any import with notes >255 Characters as that is the limit. We have been using Marketo for 2 1/2 years and never once had a problem loading endless amounts of characters into that field. Now we have to change the field type to "text area" which will allow thousands of characters. Realistically 255 charatcters is nothing. (Geez Twitter allows 140) Unless the sales and field marketing team will be putting notes in some kind of short form 255 will never cut it.
The issue is that now to fix the fields to be "text area" we must disconnect that field and take it down while the repair happens-then relink each field to every form etc. The crazier part is that while the csv import will not allow >255 characters, you can import your leads without the notes and then manually look each one up individually and copy and paste your note. Why is there a 255 character limit for imports-but not on the front end if you copy paste?
Been trying to find the best solution now as manually copying and pasting individual notes is tedious, time consuming and confusing. Our Marketo Admins are trying to figure out the best way to remedy this without disabling every form.