I finally figured it out. When I do the filament load with the external spool, I select the filament icon in the panel. There, the external spool is already linked to the left extruder. Not sure if that’s the default or if I did something that linked them together. I then go through all the load filament steps to purge the filament successfully and get it ready in the left extruder.
The problem comes when I try a print from the panel and select the external spool. After having done the filament load, I assumed the print with the external spool would be to the left extruder as well. Late in the night after trying a number of things, I finally noticed as I’m going through the panel print menu that the small line above the external spool says it’s going out the right extruder. Not sure why the print menu sees the external spool differently than the filament load. I didn’t see a way to change this from the panel print menu.
But, I went to the Bambu Handy app and there, I was able to select custom setup and link the external spool to the left extruder then send it to the printer. This finally got the left extruder working!