I'm having the same issue too. Hope Apple team can do something to fix this, and i have raised a Feedback ticket FB13190617.

Hi Dear Apple experts, We updated the HTTP2 related feedback ticket FB7857393 with latest non-working and working device logs. We can find some obvious difference by comparing the 2 logs, could you please help to take a look into this? We can see an error " Thermal pressure level above 0 returning NO" in non-wroking device MDM log, and after that the received APNS message was deleted. You can find the detailed logs in the feedback ticket. Thank you! Zhaoying

Hi, Thanks for the response! We filed an Apple feedback ticket FB7857393, with sysdiagnose log attached along with the reproduce timestamp. Could you please help to check this feedback ticket? Please let me know if need any further information. Thanks, Zhaoying