Pressing space doesn't check all selected files when committing

Change a few files in a git-controlled project, open committing, select all and press space. The entire selection must be checked but instead just the last one is.

This user experience is so poor I can't believe you still have it after all these years. It even defies standards because those mandate everything selected must be checked. It's also impossible to work around because the context menu is almost completely useless with its only two options of selecting everything or nothing.