Claude, thanks for confirming my suspicions. I like how you assigned tag values in tableViewForColumn, I hadn't thought of that. I think I will use that but assign the same value for all cell views in a given table since my bindings don't need row and col info to do their job. I like your use of multiplexing, which is new to me. Would you mind clarifying a few things? When setting the mux value what is column.? Is the trailing dot a typo? The comment after that line seems to suggest a conditional but I don't see it in your code. When demuxing what is highWordTag? Thanks for the help!

I had the client upgrade to the latest version of MacOS and the issue resolved.