Thank you!
After reading your comment, I got to thinking I'd seen a targeting option somewhere. And so I found one in the UI settings screen, made a change, and my hard targeting seemed to stick after.
The option is called "enable mouse soft targeting" and I disabled this. I never use the mouse to target, only auto-target sometimes, but mostly hard targeting with the tab key.
Now I only tried this for a couple hours tonight and need to test more with a few other toons, but it seems much better for me with this option disabled. So, it looks to be so far that for some reason soft targeting via mouse is overriding the tab key hard target. Certainly never used to be like this.
If anyone else can test and report back your findings, that may help us. I will also report back in a couple days to confirm/deny what seems to be a possible workaround to this issue.
Something to note however, this setting is character specific. So if you're testing this setting change over multiple toons, you need to change for each one.
I thank you all (now, and in advance) for your feedback
...J
PS: No comment in this thread from the powers that be. I am once again disappoint. Shame on you turbine!