Can't add Sims from gallery

@NiaNiaNiaaaa I have not done 'replace' (tried recently and it didn't work for me , but I assumed it was the manner in which I wanted to 'replace'. However, I just tried this with a sim and found the following:

1. If I went into the worldview and selected to 'Create a New Household to Move In' in the bottom right corner, I get an open CAS with a new, Sims auto-generated random sim. If I then, with that CAS still open, click 'Gallery' and choose a sim from my Library to 'Place Household', I get the option to merge or replace. When I chose replace, I got a half-greyed out screen with him merged with the household (still in CAS) and no options... it froze the game and I had to exit without saving. 
2. If I went into the worldview and selected to 'Create a New Household to Move In' in the bottom right corner, I get an open CAS with a new, Sims auto-generated random sim. If I then, with that CAS still open, click 'Gallery' and choose a sim from my Library to 'Place Household', I get the option to merge or replace. When I chose merge, the process seems to act as expected. I see the sim then included in the previous household in CAS.I didn't want the random sim to stay, so I clicked the "X" next to her thumbnail in CAS and chose to delete her. Alternatively, I could have kept her also. I see the options expected before exiting CAS... to save the household (folder) to my library (or upload to the gallery), or to click the checkmark at the bottom to 'play' the household... which brings me to the moving screen in worldview where I see the normal move-in options. 

I'm not 100% sure if this behavior is different than in the past. If this is not the what you see when you do the same, you may want to try the following (if any steps vary from what you tried) to see if it makes a difference: