Multiple persons have reproduced this on various iOS 12 devices.
One cannot select (“paint”) text with a long press after message composer has been used. So repro steps are simply:
- Edit a post, save
- Try quoting something with a long press on the text - nothing happens, the UI dialog does not appear.
Broken since 2.1 stable (we use only stables), reproed in Try. Basic UX regression, so a solid candidate to be backported in the stable branch.