Had the same problem with the same plates. We eventually figured out that the fingerprints where from the press operators when loading the plates to the press.
We solved it by changing the gum. We used the finishing gum on a 1:2 dilution. We changed to 1:1 and the problem went away.
Hope it helps.
Edit: I just remebered another thing. At the time we used Fuji's FN-6E gum. At the time of the problem, our Fuji rep advised us to change to another gum (besides changing the dilution). So, after we finished all the FN-6E gum we had in stock (without further issues), we changed to Fuji's FG-8E gum. We kept the 1:1 dilution, and haven't had any issue since.