Here is what worked for me to resolve this. Trashed AppStore XCode 12, downloaded XCode 12 xip from Dev Downloads section (GM build no longer available). Also downloaded and installed XCode 12 cmd line tools but they probably have nothing to do with this. Its exact same build as AppStore one but for some reason it just works, no more crashes accessing docs. Likely has something to do with AppStore delivery or specific way/s it installs XCode.