I have checked it now: Search by content plugins isn't supported in file system plugins, archives, and on FTP servers. This is also true for the internal tc plugin. I will add a message to the user that the chosen combination doesn't work.
In the FS custom column config there are a few basic tc.* fields which can be added to the view. I think this would be also the best solution for the search - only show supported fields.
A message should only appear when the user mixes things e.g. loading a search pattern with a local path and content plugins rules defined and then entering a FS plugin path - very special case.
I also wonder why it seems the plugin-specific fields don't appear in the search.
Request: It would be great to also have tc.Full Name and tc.path provided by TC.