Telegram for Android v10.9.1

When I'm open to a secure chat, and then the screen times out on my phone, so that I have to use a code to unlock my phone, but then Telegram doesn't ask me for a code to access it. So far, this just happens when I'm only in a secure chat.

What should happen is that I unlock my phone, and then have to enter my code to access Telegram.

It works if I've powered off my phone, though, where I'll have to access my phone code and also a Telegram code.