In XCode debugger examine Message and Media database entities created from raw notification JSON string by translation functionality written in C++. Ensure also that SQLiteQueryExecutor::replaceMessage() method gets called. execute this process for all message types we define in Comm that hae generate_notifs flag set.
Comment out set_encryption_key method in SQLiteQueryExecutor (to disable encryption) code build app on an emulator, launch it and immediately kill. Then send a message from another client. Download comm.sqlite database from XCode. Examine its content in some sqlite explorer (vscode has a pretty good one) to ensure that messages are there even though app was not launched after sending message.