I have been having the same issue with persistent crashing following update to Catalina. I have followed the ‘fix’ you outline (in fact, the privacy settings were already correct) and the issue has not resolved at all.
I have been in dialogue with Zwift support and they only offer the same fix as you and have now suggested going through the pain of rolling back to Mojave iOS.
Is anyone else having the same issue? Are there any other ‘fixes’?