Beginning this morning (30Aug2021) cannot add new individuals to a family -- why!
We have tested this and it appears to be working as it should. Please try again to see if the issue has cleared. If not, you may like to try clearing your browsing history (cookies) and perhaps also change the browser you are using. Both these things can affect how FamilySearch works on your computer. The following articles from the FS Help Centre will give more details:
Hope this helps.1