It very much sounds like the version 1.8.6 has not been properly installed as the session info suggested. Unfortunately, this does affect the functionality.
As I understand KNIME is working on a solution but until then you will have to compile it yourself since there are no pre-compiled versions available.
The linked articles (1) would still be relevant. As well as this thread:
Maybe @Mark_Ortmann could advise us as to when we might be able to expect the blog entry dealing with the Rserve and MacOSX compiling problem (that sometimes compiling does not work or needs a lot of effort)