unable to install iOS beta: integrity cannot be verified

I've been using the iOS beta.  Recently I'm getting repeated prompts to install an update but it never installs properly.  I gave up today and deleted the app then tried to redownload it from appcenter.  It fails to install but now says "This app cannot be installed because its integrity could not be verified".   Microsoft is installed as an Enterprise App publisher and the various other beta apps are working.