I assigned the Key CTRL+F to the Command NVDA-Search [.]I do the same thing, and this is still working fine for me in Outlook 2019.
Can you tell more about what you mean by it doesn't work?
What does it do or not do?
What does NVDA input help (NVDA+1) say about the key command?
Have you checked in input gestures, to make sure it is still assigned?
"The first principle is that you must not fool yourself and you are the easiest person to fool." - Richard P. Feynman