Its even ruder to answer your own question but here goes...
I fixed the problem by uploading (again) the index template to the elastic server. This was exactly the same template that was uploaded when we upgraded from 7.7.1 to 7.8.0. I then deleted and recreated the index pattern for filebeat referencing the replaced template. I then forced a rollover in the ILM, and when documents started appearing in the new indexes I was able to reference them in Maps with no errors. I then went back and re-indexed all the existing indexes that were causing issues, and then I was able to reference all these indexes with no errors, and create Maps with data in them.
I'm not sure what caused the original problem, and how the data got into the indexes that caused the geoip information to get mistreated, but now all the dashboard maps seem to be working.
Ho hum....