OK understood, but since this is a public forum I was hoping somebody else had run into the same issue with v5 and had a solution. Both installs are on the same server, have all of the exact same system parameters including using the PHP version, GD library settings, Joomla version, etc., so until I can migrate to v9 I'm stuck finding a solution. By the way it doesn't matter which editor I use either.
Regarding migrating to v9, what is protocol for using article tags? We used this extensively in v5 but they don't carry over to v9 templates.