Sorry for late response. Was traveling for a couple of days.
I've done the additional re-install, and am now running a bunch of experiments with the fresh install. If I run into more strangeness, I will document it and post here.
Nevertheless, I still find the design of the "Sessions" function a bit odd and unintuitive (for me). Ordinarily, when I am saving a software configuration (or a document, or whatever), I create the configuration, test it to make sure it is doing what I intend, and then select a definitive "Save" to capture the properly tuned configuration.
In the case of grsync, it seems I need to name the configuration FIRST, then enter the settings, then execute the command, without being sure that I am getting the results I want. This is why I always run a Simulation before doing a backup with grsync. To be honest, I can't tell WHEN grsync is actually saving my session configuration. And, if I need to fine tune the configuration, how do I overwrite it? Something about the way I think --- don't make fun of me now
--- makes me uncomfortable with this arrangement.
I am far more at ease with the Export function. Here, I can set up a configuration, fine tune it though simulations to get only the files I want, with the attributes I want, and THEN choose "Export." I then know that I am exporting (saving) the finished product, and I can give it an appropriate name. I put all these exported session configurations into a folder on my backup drive. I also paste each exported configuration into my grsync.ini file, so it can be conveniently recalled from the drop-down menu in grsync.
Another option is to simply save the rsync command generated by grsync, and then use the terminal to run it at later dates. However, I still like the convenience of grsync for setting all the flags, generating the command, and providing a simple way to test (Simulate) the command each time I use it. Many times, the Simulation has protected me from copying files I didn't want to send, or from overlooking important files that might have been skipped otherwise.
Sorry to have made a mountain out of a molehill. I appreciate you patience in helping me find my way. I will be experimenting a bit more to see if I can gain any confidence in the "Add" function of grsync. If not, I have the above workarounds that are really not all that inconvenient. With something as important as backups, I need peace of mind.