Thanks Pam.
I have tried to travel again with the same result (my sims don't appear in the destination town). I have tried it with the same sims as previously and different sims (and get that same result).
I have also emptied my family inventory, so that there is no longer anything there.
I have the launcher set to automatically download game patch updates, so as far as I know, I'm at the current patch. It did just update the store content. The launcher tells met that the current version is: 16.0.136.019001 ... Is that what it should be saying?
One further thing has happened. The thumbnail picture of my sims (in this game file) is all distorted. Their arms and what not are all over the place, and sims are with incorrect partners.
At one stage through the process, my keyboard went haywire on me. None of the letter/number keys would work, delete put in an underscore and esc dropped me out of the program. That was the first time I attempted to add Majel's 5th trait back in. I had no choice but to reboot my computer (CTRL-Alt-Del) wouldn't even work.
Edit: One more thing happens that I just remembered ... I sent one of the household to the mailbox and collected the mail. Various townies sent gifts to the household, all of which became gift boxes and described as 'omni plants' in that sim's inventory. She also got a stack of bills in her inventory, despite one of my sims having 'no bills ever' as a LTR. I can't get rid of either the bills or the gift boxes from her inventory, not even after using the enable cheats cheat.
Edit 2: Adding Majel's trait back in worked without a hitch, it appears.