Shadow performs sim actions with no sim present

Product: The Sims 4
Platform:PC
Which language are you playing the game in? English
How often does the bug occur? Every time (100%)
What is your current game version number? 1.52.100.1020
What expansions, game packs, and stuff packs do you have installed? All except Island Living, Seasons, and My First Pet
Steps: How can we find the bug ourselves? Have a sim go to an event off residential lot.
What happens when the bug occurs? Not sure if this is the right place, but here goes. Just finished another test. Sim went out to the opera with a friend sim, one of those rabbit hole 'I got tickets, want to come?' things. Sim walked off lot to go. Game speed stayed at 1, not speed up as expected. A short time later a shadow-like thing suddenly appeared in sim's living room, fluttered over to the chess table, and began playing with all the usual animations. Sim's portrait in the lower bar was greyed out, and had been once the sim left the lot. Shadow thing did various other things before going to bed, including gaining a skill point. Could hear sim's voice, but no sim seen. Decided enough was enough so bailed without saving, thinking that when went back in would start at prior save point. Wrong. When went back in the sim was back, and at the place where had bailed out. The gained skill point was there, too. So not only was there all that odd behavior, but the game saved when it should not have under ordinary circumstances. Something else the June patch broke?
What do you expect to see? Sim to walk off lot, game speed go to 3 while sim gone, sim return and time back to 1 When exiting a game without saving, when re entering game it should be at the last prior save point, not where one left the game.
Have you installed any customization with the game, e.g. Custom Content or Mods? Not now. I've removed them.
Did this issue appear after a specific patch or change you made to your system? Yes
Please describe the patch or change you made. June patch, which happened automatically

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Above data should be enough.  Took screenshots, but have no idea how to include them.