Up until recently it seemed reasonable to assume that all StoreKit observer and delegate methods were called on the main thread. I'm not sure if this was documented, but I had ASSERTs in the relevant methods to check this was the case and they never fired.Since updating to iPadOS 13.1 I have discovered that the productsRequest:didReceiveResponse: and requestDidFinish: methods of SKProductsRequestDelegate are no longer called from the main thread. It's best to assume that request:didFailWithError: is also affected, although I haven't tested it.Given that these methods are typically used to update application state, it's now necessary to ensure this is performed in a thread-safe manner. I think the least intrusive solution would be to schedule the work to be performed on the main thead using dispatch_async(dispatch_get_main_queue(), ...).I'd be interested to know if anyone else can confirm this.