It looks like
The assembly: Enyim.Caching.Log4NetAdapter (version 184.108.40.206) 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 220.127.116.11 although version 18.104.22.168 is supplied in the package.
The same assembly supplied by nuget.org is built against Enyim.Caching version 22.214.171.124
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.