Possible variable rendering error in Illustrator

hi—the first image is how the innermost part of an inline asterisk is supposed to look. the second is how it renders in illustrator. I wasn’t sure where to start looking for causes to the problem.

UPM is set to 1000, grid & subdivision is set to 0 (considering how fine the details are in this one). have I missed an export setting, or does this seem more like an Adobe rendering error?

edit: this only happens in the variable & ttf export. static instances in OTF render as expected.

05-PM

my UPM was too small. upped it to 2000.

Variable fonts to not support fractional coordinates.