Apple Pencil lagging on Notability

I have a 12in iPad Pro that I use for school. Notability has worked great for the last 6months; I use it for all my notes. I've had no problems until last week when I'm getting constant lagging w/ the pencil (2nd gen).

Yes... I have already:

1. Restarted it
2. Closed other apps
3. Changed the pencil tip
4. Disconnected and reconnected the pencil.

Is this a notability issue or an iPad issue? I don't use the pencil in other apps so I don't know if the issues is outside of the app. Anyone else having this issue? PLEASE HELP; it's really affecting my study flow.

Before I leave a negative review on the app, I'd love to know what's going wrong!

[Re-Titled by Moderator]