Trouble Using Numbered Lists w/ Heirarchy

I would like to create a hierarchical numbered list, but cannot figure out how to promote and demote with consistency. seems to demote, but the backspace/delete key does not promote, it only undoes the list feature for that line. And sometimes it does wacky things, like promote or demote a line that I wasn’t even trying to instead of the one I was actually trying to. What are the proper keyboard combinations to promote and demote? Is this a known bug?

Shift-Tab will outdent the line.

Thanks! I thought I had tried every possible keystroke combination, but apparently I missed that one!