This is a well known issue here in these iPad support communities.
This intermittent, unresponsive touch screen issue affects a continuing, growing minority of iPad Pro users/models across all 4 years of iPad Pro models, as well as the new 2019 10.5 inch screen iPad Air 3.
Take a look at these long standing, longer posts on the subject of this intermittent, unresponsive touch screen
issue, below.
There is STILL no “official” confirmed iOS updates, solutions/fixes, from Apple, after nearly 18 months, now!
None.
That is because this issue is either STILL only affecting a growing, but still very small minority of iPad Pro users OR iPad Pro users are simply NOT reporting this issue enough here in these official Apple iPad support communities OR simply NOT posting enough feedback to Apple about this intermittent, unresponsive iPad Pro touch screen issue to alert the proper responsible and cognizant Apple employees and teams and get them working on this iPad Pro touch screen problem.
iPad Pro touch screen intermittent unresp… - Apple Community
iPad Pro screen unresponsive - Apple Community
iPad Pro 12.9” not responding to touch in… - Apple Community
The best you can do is to continue to alert Apple to this growing issue and hammer the Apple iPad feedback pages mutiple times on this issue.
The only way to get Apple to, DIRECTLY, listen to you is to use their feedback portion of their website.
iPad Feedback
http://www.apple.com/feedback/ipad.html
Cognizant Apple employees read ALL feedback generated from all of the various feedback pages and transfers the data to the proper and responsible Apple teams and personnel , but NO Apple employees will ever respond with any type of direct, individual replies from the feedback you post.
You can post as much multiple feedback about this issue any time.
The more users that post product feedback about any product issue, the faster Apple is made aware and starts working/continues to work on a fix/solution for a future software update.
As I stated, this intermittent, unresponsive iPad Pro touch screen issue has plagued a small, but growing minority of iPad Pro users across all 4 years of iPad Pro models for just about 18 months, now!
Also, I suggest contacting/reaching out to Apple Product support and services.
Tap on the first link below and scroll down some to get to the Apple Product Support section and phone numbers for your location/region.
https://www.apple.com/contact/
OR
https://support.apple.com/en-us/HT201232
Best of Luck to You!
