Views caching not working for Taxonomy listing pages
Have you tried doing a print_r(), dpm(), etc. on the cache_get() and cache_set() functions to see what's going on? The output of this tends to be somewhat verbose, so I generally like to do an error_log(), then go to the PHP error log and see all the calls to cache_get and cache_set to see if I detect a pattern. This would give you a concrete idea of what and what is not getting cached.