Finally got a reply from Notability! Here's what they said:
"Thanks for getting in touch and sorry for the trouble! We recently introduced Document Scanning which may take more effort than usual, while your previous images index, so it may drain the battery faster than normal and make your device warm. Once all of your images have been processed, though, things should return to normal.
Please let us know if things haven't settled down, and we can investigate further."
Soo considering I have 700 lectures on notability, I got a feeling this is gonna take a while. I think I might just plug in my macbook overnight and let it run its course (probably gonna have to pop open my window to help keep it cool). I think I'll give it a shot tonight and let u know how it is tomorrow. Really hoping that this is the solution...