Version 3.0.1, running on Mac Mini El Capitan.
I have not tried to reproduce this on any other platform.

I have the processing preference editor.tabs.size set to 4.

When I comment/uncomment, each time one space is removed from the indentation of curly brace contents until such is eventually aligned with the braces. It does not proceed further. In the case of deeply nested code, the issue gets a bit more interesting.

I can submit my preferences and theme files as well, because there may be some ancillary interaction responsible for this issue.