Argh - thank you both for your help. I have tried a number of choice combinations on the flow step and it is still overwriting lead owner everytime regardless.
What I want to happen - that I thought I was setting up in the image below - is if the SFDC Type is empty (that is they don't exist yet in the CRM) then assign then sync the lead and assign to the queue, "User: Marketo Sync"
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otherwise, if the lead does exist, do nothing (or at least don't overwrite the lead owner)
I set myself up as a lead and have been running through this flow, and each time it is changing the lead owner to "User: Marketo Sync" even though i'm a pre-existing lead in the CRM w/ a SFDC lead type populated with "Lead" as a value (so not empty)...
I can't tell what i'm doing wrong in the logic here...
Thanks again.