The game doesn't always respond to scrolling of the mouse wheel in the latest snapshots.

What I expected to happen was...
I use a mouse with a "notched" scroll wheel. Typically scrolling one notch will move the selected item up or down by one in the hot bar, or move the scroll bar up or down by one bit in the creative menu, and this is what I expected to happen.

What actually happened was...
The game doesn't respond at all when I scroll my mouse wheel by just one notch— I can scroll notch by notch and nothing will happen indefinitely. In order to change items or move the creative inventory menu, I have to scroll somewhat vigorously, quickly scrolling by several notches at a time. Then the game realizes that I'm scrolling, but instead of selecting the next/previous item in my hot bar, it usually jumps two or more items ahead/behind. This is extremely annoying, and is one of those little things that just makes playing the game strangely very difficult.

Tested this with two different mice (both with notched scroll wheels) on two separate Mac computers, each running clean installs of Minecraft. Neither one detected scrolling. My mice work fine in all other programs, and in MC Java Edition 1.12.

Steps to reproduce:
Should be reproducible on any Mac environment running High Sierra and on the latest snapshots. Not sure about earlier versions of macOS (or earlier versions of Java).