I have the same problem, probably for a while, but didn’t notice it before. Searching other topics I found this link: https://kriesi.at/documentation/enfold/install-enfold-theme/#reinstall-or-update-using-ftp
Tried it and it went all wrong… The child theme was broken after updating. So now I’ve put the backup back, but still don’t know how to update without messing up my website.