Feeds not autoposting – Unable to select "Blog User" for feed

I’ve recently installed Mutli Press, added 5 rss feeds, customized for 2 items for each feed. I’ve setup auto post, and checked the feed items, and all 10 items are pulled into that list.

When I setup the feeds, I click into the “Blog User” drop down box, but none of my users appear for selection. No box opens.

In my Users pane, I have
Administrator (2) | Author (13) | Contributor (8) | Subscriber (25,444)

Currently, there are no auto-post items being added to my blog roll. Could this be due to the lack of user selection? Any assistance would be greatly appreciated.
Many thanks.

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