Huawei P20 - Why can't I preview my messages?

[Android Central Question]

Hi everyone! I have a question. I used to own S7 EDGE and usually when I'd get multiple messages, let's say on Whatsapp, I'd be able to actually "preview" them on my lock screen which allowed me to find out the content of the said messages, without actually going to the app itself. Kinda like a cheat sheet, so to speak

Now, w/ my P20, I can't seem to do that. It just doesn't want to. I'd like to provide a screenshot, but links aren't allowed...

Basically in the screenshot I took I have 7 messages, but I can't "stretch" them down to reveal the whole content of the aforementioned messages.

Thanks,
Mark.