Re: sims 4 cats and dogs and build mode cannot be saved
I figure you're referring to custom content? CC it's a constant struggle, in checking for updates especially after a large update / pack such as the latest one, you simply have to check it all by removing 1 'cc folder' at a time and narrowing it down. Since the Cats and Dogs patch, there are many reported broken mods and cc. For example; I had to remove all Custom Recipes as only 1 person has their's updated.
Over at SimsVIP they have created a very large post to include all the broken CC and Mods worth having a look there, also the Sims 4 Studio is worth having even if you don't make Custom Content, as there are always 'batch fixes', which, with 'one click' it'll fix all CC sofas and beds for example and or all 'lighting'.
Hope this helps.
Sasha