Game crashes when disabling packs

OK, I have found a workaround.

The last save had data from different packs, and I guess the game crashed when showing the loading screen, with the most recent played-with family displayed. I launched without disabling packs, opened my Base Game only save, saved it again straight away (so that now it is the most recent save) and closed the game. When I relaunched disabling all packs, this time it worked, with the caution message that I might lose some game data because of the lack of packs, but as my initial save was base game only, I knew it would be OK.

But this crash had never happened to me before, even though I played with base game only, and then with packs, and then with base game only again, so I do not know how the issue was generated.