Implementing an iOS QuickLook Preview Extension

Hello, I'm working on a document-based app that has a companion iOS QuickLook Preview extension. I'm having trouble makeing the system use my QL preview extension for my particlar file types. It works *sometimes*, but not for all of my files. For most files, it just shows a generic "File" quick look view with the name and size of the file.


Peek+Pop previewing works just fine in Files.app. It's peeking in the Siri Search view that doesn't work 100% of the time.


Is the WWDC 2017 "Particles" sample code available so that I can check all of my Info.plist keys are correct here? This was from the talk "Building Great Document-based Apps in iOS 11"


I have already set my CFBundleTypeRole to "Editor" and LSHandlerRank to "Owner" for my particular document UTI.


Thanks for any pointers!