WKWebView display of PDFs stopped working on Big Sur

Got a fairly large app with a build setup that I did not do. We use WKWebView for embedded browsing. On upgrade to Big Sur, displays of PDFs in those web views stopped working.

I've built a stand-alone app that can load PDFs into WKWebViews from the net and from the local disk, so I know what we're trying to do is still possible. Both projects have:

Code Block
<key>NSAppTransportSecurity</key>
<dict>
<key>NSAllowsArbitraryLoads</key>
<true/>
<key>NSAllowsArbitraryLoadsInWebContent</key>
<true/>
</dict>


in their Info.plist files. My test project has an App Sandbox in which I've turned on "Outgoing Connections", the main project does not have an App Sandbox, and loading and display of HTML pages into those web views works just fine.

Anybody got clues? I'm sure it's a project setting somewhere, but I don't know where to start.
WKWebView display of PDFs stopped working on Big Sur
 
 
Q