`array` optional position argument `[b]` appears to not work

Created by: tylercecil

Issue Summary

My apologies in advance if I am mistaken / making no sense / filing in the wrong place.

This JS Bin shows a minimal example. You can see that top aligned seems to work, however bottom align works the same as top (center align works fine).

By chance, I noticed 2.7.5 seems to have the correct behavior. I am totally ignorant of the Mathjax project and its history, though, so... all it tells me is that there was a time when it worked.

I found #2083 (closed), which may be related?

Technical details:

• MathJax Version: 3.0.1
• Client OS: Arch Linux
• Browser: Chromium 80.0.3987.149 Arch Linux