Pinch zoom is flickery as well..
The main thing is the highlighted text isn't getting save . Kindly look into it.
It seems that your app is crashing due to some reason while highlighting the text.
Please perform the following steps :
1) From Google market place, please download an application that displays the device logs. Some of the free apps available :
2) Repeat the steps to reproduce crash
3) Share the logs that have been obtained by the above apps with us along with the device and OS version details.
This information would greatly help us in ascertaining the reason for the crash on your device.
Awaiting your response
I had the same issue with my MiPad. I got the following answer form a staff member:
Please try to Clear the Cache of the application and then open it.
Otherwise try this:
Uninstall Adobe Acrobat from the MiPad
Download the APK file from here and install it.
It kind of worked for me on a freshly reinstalled ROM (latest stable European ROM). Still have to reboot the device after about a day, but otherwise it's stable. Definitely better, than with the app available from google play.