Sophia's Snack - No, my inventory isn't full!

Describe the problem. Be as specific as possible!:
Sophia's Snack quest cannot be completed because of full inventory, although it really isn't...

 Images of problem

Glad to see yet another bug I reported in Tespia didn't get addressed

UPDATE: Quest can be completed if you give Sophia 20 Sap of Ancient Tree.

Misprint of the quest log probably.

Not a misprint in the log. When you have 10, you get a "quest complete" red notice, the icon over Sophia's head turns to a closed book, she even attempts to give you the quest reward, but fails.

The number of items to get is apparently written, separately, in 4 places.
1) The NPC text when the quest is given
2) The quest log
3) The quest data, as shown by Quest Helper
4) The list of items to be removed from inventory when quest is turned in (internal to the program, not shown except as "you have lost items" messages at the proper moment).

In Tespia I noticed quite a few cases where the first three didn't match. (There were also a few in pre-BB GMS, as Justin notes below). However, the last two always matched, in my experience, to the point where I didn't even know the fourth exists, until now.

Must make changing quest requirements an extremely tedious and error-prone job, when you have to manually change 4 places.

There was a similar issue with a zipangu NPC having a misprint and requiring x more cucumbers when the quest log says x amount. Don't remember the EXACT specifics, but yeah.