It looks like
The assembly: Enyim.Caching.Log4NetAdapter (version 18.104.22.168) supplied in the zip package (Available at: http://packages.couchbase.com/clients/net/1.2/Couchbase-Net-Client-1.2.7...) is built against Enyim.Caching version 22.214.171.124 although version 126.96.36.199 is supplied in the package.
The same assembly supplied by nuget.org is built against Enyim.Caching version 188.8.131.52
I am able to use logging only if I retrieve it via nuget. Using the zipped package available for download always results in a TypeInitializationEnxception.