Steps to reproduce:
Type "ndnio". Observe that one of the suggestions is "ndnio superconductor". Type a space. It's gone. Type "ndnio sup" and it's still not there; in fact even at "ndnio superco" the only suggestion is "ndnio supercomputer".
Expected behavior:
As I type more characters, already-shown suggestions that match what I'm typing must remain visible.
Why it's important: because it takes time for suggestions to appear, so by the time I see what I want, I may have typed a couple more letters, and then it disappears just as I notice it. Backspacing is the only way to get it back!