Somehow managed to change the default font of lists in one project and can't work out how to reset it

I don’t know what I did, but (only in one project) if I start a list in a blank document it switches to Helvetica. If I apply it to already existing text or below already existing text, it retains the default project font – taken from Project Settings overriding Preferences.

In other projects, starting a list retains the default font whether it’s a blank document or not.

Anyone have any ideas? I’m using lists a lot in this project, and would like the standard behaviour back.

[Scrivener 3.0.2 1506 running on 10.13.4 – on a project that goes back and forth between Aeon Timeline if that makes any difference.]