So I wanted to share the solution for an issue I was experiencing with the latest version of CaptureOnTouch on MacOS Mojave.
The P-215 is spec'ed to scan documents up to 39 inches (1000mm) in length, but by default CaptureOnTouch 184.108.40.2065 only allows 14-inch (356mm) document scans. If you attempt to scan something longer than that, the scanner will stop at 14 inches and produces a paper jam error message.
The old method of setting long document mode was to find the maintenance window and turn it on from there, and it turns out that window still exists - it's just a little more deeply buried. The path in CaptureOn Touch is:
Main Screen --->
click the pencil icon on any preset -->
Check "enable" next to "Use Advanced Settings", then hit the "Settings" button immediately below it -->
There will be a blue information ("i") icon in the bottom left corner of the advance settings dialog box. Click it -->
A Scanner Information dialog will appear. Click the "Maintenance" button --->
In the Maintenance dialog, change the radio button from "Standard" (356mm) to Long Document Mode (1000mm)-->
There is no save settings step, close all of the windows and a longer doc should now scan without issues. Below is a screenshot of the all the windows involved in the order they appear. Hopefully this helps anyone else who is struggling to figure out how to make long document scanning work!
(FWIW this whole process may be explained in the 2018 revision of the P-215 manual, but since that manual is an app that downloads for me as a corrupted dmg file, I couldn't check).