In our 11.7 release of Notability, we introduced the PDF Smart Highlighting feature.
To use this feature, long press on PDF text to snap and begin highlighting. The highlights can now be edited, styled and erased like regular ink.
If you are having issues triggering the PDF Smart Highlighter or have lines appearing in blank space - make sure you are long pressing the first word of the sentence you are trying to highlight before dragging and continuing to highlight.
Straight line highlights can still be drawn by drawing a line and holding.
If you have other issues with highlighting, or any other issues you’d like to make us aware of, you can follow the steps here to contact our support team.