Why can I not see the red line in Data Usage?

[Android Central Question]

I have a P20 Pro and some of it's features are MT6580 Hardware, Octa Core Kernel, and Android version 6.0. It could be because of the phone itself that I can't extend or decrease the limit (missing the red line), but it could be what I did. Can I get any answers?

 

[belodion]

Perhaps you've unintentionally set it far too high, so that on that scale it doesn't appear?