@jiko
To reproduce, in PushNotificationPayload.apns your category should be test\_category, same as the identifier of your UNNotificationCategory in NotificationProcessor.swift, but the notification is indeed nil when userNotificationCenter(\_:didReceive:withCompletionHandler:) is called.
I have the same issue in my project since watchOS 7 betas and till now, with watchOS 7.1 beta 3 and Xcode 12.2 beta 3.
One observation I have: if I tap on notification itself and not on UNNotificationAction, then response.notification is not nil.
Everything was fine on watchOS 6.x.
Topic:
App & System Services
SubTopic:
Core OS
Tags: