The attached image says more than what I can say in words, but in summary:
The three red boxes highlight what I added to my schema. (There are other collections but they are irrelevant to this discussion, or am I making an assumption?)
I updated the schema from the web UI.
I thoroughly tested a new feature on a fresh development database without incident. I guess that was my mistake: “on a fresh database”. Going forward I will develop on a copy of the production database.
Any thoughts on how I can remedy this? I can’t roll out this new feature until after this index finishes building.