a screenshot would be helpful. also consider resetting the pa for excel user profile as a similar test - you can find the 'Office Connection' folder typically c:\users\<user>\AppData\Local\Cognos or more conveniently by using the 'view logs' button in the Options dialog for PA for Excel and then going up path. just rename the folder and when the addin restarts it will make a fresh one of default settings. (you can swap the folder back when the test is done)
that said, i wonder if a desktop firewall rule is impacting the outcome here.
please consider contacting support and I'm sure they can help sort it out.