It looks like
The assembly: Enyim.Caching.Log4NetAdapter (version 126.96.36.199) 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 188.8.131.52 although version 184.108.40.206 is supplied in the package.
The same assembly supplied by nuget.org is built against Enyim.Caching version 220.127.116.11
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.