Can't connect data source

[BogeyDBA]

I've never seen this before, but I have a user who is not able to connect a dataset source to a gateway data source.  We've confirmed permissions are correct, deleted and republished the report and dataset, and done all the nessecary browsers steps (logged off/on, cleared cookies, tried other broswers).  Picture for what we're facing below.  You can see the green check box next to the data source, but there is no drop down to select the right one.  

[GilbertQ]

Hi @BogeyDBA 

Can you make sure that the names for the data source match exactly even with the upper case and lower case?

Also can another person who has permissions connect to the data source?

If another user can, then possibly compare their permissions