It's been an issue off and on during the time I've owned my RT-700. A while back there were issues with the app not giving any notifications. It was addressed successfully with an update to the app a while ago and alerts worked nicely.
More recently we've seen issues with notifications sometimes being delayed or not happening at all. You can still connect to the grill via WiFi and control it, so it's not a WiFi or 2.4 vs 5 GHz issue - but alerts are affected. The general speculation is that there's some issue with their cloud infrastructure. It tends to be noticed around holidays when more people would be using their grills, so perhaps increased data traffic is a factor. The truth is none of us know for certain. More people using their grill means more people would see the issue but doesn't necessarily mean the increased traffic is the cause.
If people are displeased with the issue, I'd suggest contacting Recteq directly. Call Ray himself. This is a private forum and to my knowledge, they don't monitor it for discussions.
It will be interesting once I start using the grill. It arrived Monday, I thought my first cook would have been yesterday but the wife had other plans. I just made up some brine and will put the chicken thighs in at noon and will fire it up for burn in just before dinner. I will try it out but I also have other probes and a TP MK4 to check. It will be a good opportunity to try it out. I can also do some packet capture to see what is going on between the grill, cloud and phone. I am actually kind of shocked that the grill isn't very chatty on my network so far. A lot of IoT stuff like this is very noisy. I will dig into it a lot more but it won't be any solutions. At a high level I would say the cloud service doesn't appear to be in the US. I haven't done a full trace on it yet though. Just some basic visibility I have in my network sensors.