I ran into this problem with the native Notes app on an iPad Mini 4. It's possible this problem is limited to the iPad, since apps often have different interfaces for iPads than they have for iPhones and iPods.
While editing a note, if the iPad is in portrait mode, there is no VoiceOver feedback as to what is being typed. There is no echo, regardless of the typing echo setting, and if you try to navigate the text field by characters, words, or lines, you hear sound effects indicating that the cursor is moving, but no speech telling you where you are in the note.
If the iPad is in landscape mode, the bug does not occur, and I can interact with the text field normally. However, if I bring up the Notes app through the iPad's split view feature, the bug still happens, even in landscape mode, so I must use the Notes app in full screen mode and in landscape in order to get proper VoiceOver feedback.
I don't use the Notes app often, but the bug definitely did not happen the last time I used the app, which was a couple of months ago, so the bug must have been introduced in an iOS update since then. The bug continued to occur after restarting VoiceOver, restarting the Notes app, and restarting the iPad as a whole.
Can anyone else with an iPad reproduce the bug? How about on other iOS devices? I plan on submitting a bug report to Apple Accessibility, but I want to know if others are observing the behavior first.