So I have tiredlessly searched for more than a year now for answers on this. In have tried everything out there in every forum and YouTube video. I had a note 10 before the Z Fold 2 and had the same issues. I am so frustrated that I almost want to try an iPhone (that is so awful). Sometimes notifications are fine, other times they are non existent. Sometimes they are delayed 15-20 minutes, sometimes it is 5 hours or more. Sometimes I click on a notification and the app open fine, sometime the app finally opens 4 hours later. This is everything from the Google news app to the NFL app. Most importantly, an app called Life Reminders that in have been using for close to 5 years. In have used it to function for work and personal tasks, but it is now useless because 80% of the time, I never get a notification. The only thing I haven't tried is rooting my phone. SAMSUNG, PLEASE HELP! I don't know that this is specifically a Samsung issue, but you would think they would want to understand it. There must be some way to tell what is blocking notifications from coming through.
So after finding some people talking about their fitbit devices possibly being a root cause of this, I decided to unpair my Samsung S3 Frontier last night and try going without it for the day. Notifications and everything have been working perfectly fine so far today! It is a pain, because I use my watch constantly to keep track of steps, water intake, snooze notifications (when they work), etc. I am happy to be getting the notifications on the phone now, but this needs to be fixed Samsung!
Update, the problems are all back after a day and a half. I haven't reconnected my watch, so I don't understand how that miraculously fixed things for a short time. So frustrating.
There are people talking about this all over these forums, across devices for the past 5 years or more. If you google it, there are people talking about it all over. I don't think this is device or Samsung related. My S9 had the same problems and when I got my new Fold 2, I transfered everything over. Now I have gone as far as a full reset and start from scratch rather than transfer settings. There has to be a way to monitor log files to see what is keeping the notifications from coming through.
Now that I have "White Glove Service" with my new flagship phone, I do plan on reaching out to Samsung.
I think (?) if you are both using Google messages and have ete encryption turned on (chat features) then messages between you will not show up in other chat clients (Samsung messages, Verizon Messages)