Can't open package files on iPad in iCloud for document based app

I've got a multi-platform document based app, with package files (the "file" is a folder, but looks like a file for the user).

I can create files on all platforms, tho I can only open files on Mac and iPhone. When I try to open files (in iCloud) on iPad, the file does not open and nothing is logged. Tho the files do open when they are stored locally on the iPad.

I followed the documentation here: https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFBundles/DocumentPackages/DocumentPackages.html

I've specified LSTypeIsPackage to true and added com.apple.package to UTTypeConformsTo.

I've tried incrementing the build number.

I'm targeting iOS 14 / macOS 11, and build with Xcode 13 beta 3.

Here's my info.plist:

<plist version="1.0">
<dict>
	<key>CFBundleDocumentTypes</key>
	<array>
		<dict>
			<key>CFBundleTypeName</key>
			<string>File Name</string>
			<key>LSHandlerRank</key>
			<string>Owner</string>
			<key>LSItemContentTypes</key>
			<array>
				<string>com.mysite.file</string>
			</array>
			<key>LSTypeIsPackage</key>
			<true/>
		</dict>
	</array>
	<key>LSRequiresIPhoneOS</key>
	<true/>
	<key>LSSupportsOpeningDocumentsInPlace</key>
	<true/>
	<key>UISupportsDocumentBrowser</key>
	<true/>
	<key>UIFileSharingEnabled</key>
	<true/>
	<key>UTExportedTypeDeclarations</key>
	<array>
		<dict>
			<key>UTTypeConformsTo</key>
			<array>
				<string>com.apple.package</string>
				<string>public.composite-content</string>
				<string>public.data</string>
			</array>
			<key>UTTypeDescription</key>
			<string>File Name</string>
			<key>UTTypeIdentifier</key>
			<string>com.mysite.file</string>
			<key>UTTypeTagSpecification</key>
			<dict>
				<key>public.filename-extension</key>
				<array>
					<string>myext</string>
				</array>
			</dict>
		</dict>
	</array>
</dict>
</plist>

Does anyone know how to debug this?