PLEASE READ CAREFULLY. THIS IS NOT THE SAME PROBLEM I KEEP FINDING WHEN I SEARCH FOR IT.
I like to use OneNote for note taking. OneNote itself works fine, and I see no issues. I open a file and begin editing and initially there are no issues so far as I can tell. Maybe a bit slow, but I am using an under-powered laptop.
After a short period where I can add add section groups, sections, and pages just as normal, OneNote then decides to display the error on empty sections

Once this error is present, I can no longer create new subsections or subsection groups, but I can still take notes and add pages to existing sections and I can add new sections and section groups to the base of the notebook. I cannot add sections to to existing section groups. I cannot create new (sub-)section groups. I cannot rename existing section groups, subsection groups, and sections. I cannot rename existing section groups.** It is as though OneNote decides to partially lock the ability to edit certain aspects of a notebook. The notebook still syncs changes to the files as normal. OneNote still allows me to write and draw as normal.
If I try to move a section to one of these "read-only" groups, then I see this:

The only known fix:
THE ONLY FIX I HAVE FOUND IS TO CLOSE AND REOPEN THE NOTEBOOK. THIS WORKS FOR ~30 SECONDS BEFORE ONENOTE DECIDES THAT SUDDENLY I CAN'T USE ONENOTE.
A kinda fix:
I can open the file explorer and create the files and folders that I need. OneNote has no problem with this, but won't do it itself. (╯°□°)╯︵ ┻━┻
This all occurs
- even if I restart
- onenote
- google drive (which is the file syncing program I am using to sync my notebook across devices)
- my computer
- even if I close google drive so that it's not active when I reopen the notebook
- even if I change the file settings so that the files are not read-only
- even if I uninstall and reinstall
- even if I open OneNote as an admin
- even if I open the notebook from a new location
- even if I log into office from a different account.
PS - I can't get my surface to stop autorotating and disabling the keyboard when I pick up the surface to readjust myself or the computer.
EDIT: Upon further investigation it may be related to the fact that the notebook is currently stored on an external MicroSD card (which is for all intents and purposes superglued to my machine) instead of the local disk. Not sure how or why that would affect this.