According to a pattern of online user reports, the smaller variant of the iPad Pro 2018 is afflicted by a bug that throws its touch-reponses off when a glass screen protector is installed. This results in a host of ill effects, from ghost touches to diminished passcode-entering accuracy. However, iOS 12.2 reportedly includes a fix for these issues.
https://www.notebookcheck.net/New-iOS-12-update-appears-to-fix-known-11-inch-iPad-Pro-2018-screen-issue.415206.0.html