The first thing to do is to check out your content in a new save. You can use NRaas MasterController plus MC Cheats to grant inventing skill (click on a sim, NRaas > MC > Advanced > Skill Level), and DebugEnabler to teach a sim the inventions. If everything works, then it's just your current save, or maybe your current household or sim, that's somehow borked.
Otherwise, the pet shop not working makes me think your ccmerged.package might be corrupt. It's necessary to make premium store items function correctly. I'm not sure whether the Ultimate Career Bundle functions as premium content, but the pet shop cash register does. You can rebuild your own ccmerged by downloading all of your premium content and these two items into a clean game folder, then just replacing your old ccmerged with the newly generated one. Or you can skip all that work and download this file from NonaSims:
https://nonasims.wordpress.com/2012/05/17/dcbackup-ccmerged-package-and-your-premium-content-items/
Be sure to test the content in a clean game folder, just to make sure it's working. And, of course, delete your cache files before proceeding.
If rebuilding or replacing your ccmerged doesn't help, you likely have a corrupt .ebc file in DCCache. If you were reinstalling the content into that file, it would probably continue to not work properly. You could uninstall the Ultimate Career Bundle and pet store from your game folder and then reinstall them into a clean game folder. Then take your new .ebc file and rename it so that it's numbered one higher than the highest in your existing game folder (so if those are dcdb0.ebc through dcdb4.ebc, rename your new one dcdb5.ebc). Place this file in DCCache in your old game folder, grab the Library file that corresponds to the pet shop itself, put your old folder back in Documents\EA, and test things out.
