A few times now, I've noticed that even though the info appears to be mapped correctly when stepping through the list import process, once the data is in, it's all in the wrong spot. So, I delete the list and do it again. Anyone else?
I have not had this issue. Have you gone into the admin section and looked up the field names? It could be that two different fields have the same name. For example, maybe one field is on the lead and other is on the contact and they're not mapped together in Marketo.
Turns out, one of my field names (from SFDC) had a comma in it. Supposedly, that was the reason. However, some lists imported ok.