subversion "compare with branch" bug, or misconfiguration?

Whenever I attempt to use "Subversion -- Compare with Branch" function, I'm given a list of branches correctly, but selecting one results in an error dialog saying " [svn url] refers to a directoy".

When I select "configure branches", I see an odd svn urls defined for trunk and branch locations which seem to  be the cause of the error.  It should be:   svn+ssh://username@example.url/svn/ , but is instead svn+ssh://username@example.url:22/svn/  (note the inclusion of port number).  When I correct these, I'm then able to "compare with branch" without error.  However, my changes seem to get lost between sessions.

About my setup:

When performing svn operations from command line, I use URLs such as "svn+ssh://username@example.url/svn/".  I've shared keys with the target server.  I don't believe I had configured IDEA's svn auth to use keys (it was done awhile ago).  Instead I think I had just defined my username and password.

My IDEA projects are structured like so:

root project dir, non-versioned
    - an unversioned pom.xml file in root project dir, and IDEA ipr/iml files
    + module A dir ( versioned )
    + module B dir (versoined)

I'm using IDEA Maia #10781, but this has been a problem for awhile.

Have I misconfigured something, or is this an IDEA bug?  If so, I will create a bug report.

~ kc