There is a batch fix in the latest version of Sims 4 Studio for this. I'm not sure if it resolves disappearing bathtubs, but it's called "Fix CC Bathtubs." I'd recommend giving that a try. If it doesn't work, then someone would be happy to take a look at the file and see what's wrong.
If you are having problems seeing the CAPTCHA, please clear your browser's cache and cookies and ensure that you do not have any browser addons or extensions that interfere with the display of the CAPTCHA. Then, close the CAPTCHA window and click on the register button to open the CAPTCHA again.