After my last map purchase and install on my Fenix 5x, Basecamp no longer recognizes my watch.

Well it should still be read even if it's now in mass storage mode, but you could try switching it to MTP mode, unsure how you do that on a Fenix though.

I continued to be stumped.  I deleted activities, etc.  deleted Basecamp and reinstalled it....even plugged in my Garmin 60 CSX.  Basecamp recognized the 60 CSX, but would not display the Topo maps.  My Fenix 5X is being seen as "Removable Media (such as an SD card)".  I can't import GPX files, add new maps or see what is on the watch.  Any suggestions would be appreciated.  Thank you

Are you using the latest BaseCamp version?  There are reported issues with that when dealing with third party maps.  You could try reverting to an earlier BC version to see if that resolves it?

Thank you for the suggestion.  Basecamp is the latest version and the maps are all Garmin maps.  I would like to try an earlier version of Basecamp.....do you know where they are archived?  Thank you very much.