"Compiling UFO failed: 'h' format requires -32768 <= number <= 32767"

I’m using FontMake `3.0.0` to build fonts (static and variable). It was previously working to build static fonts with version `2.4.2`, but recently, the kerning was dropping at locations that have support/sparse sources (in static fonts only; the variable font kerning is working fine). I have perhaps fixed this issue in the past, but I figured I would just try upgrading FontMake to see if it is solved in a better way.

However, the build now fails when I am trying to interpolate one of the thinner UFO sources, with this message:

`Compiling UFO failed: 'h' format requires -32768 <= number <= 32767`

(In my build, I interpolate UFO instances, edit their data a little bit, and then generate static OTFs and TTF from there.)

Most of the UFOs are interpolating without issue, but it’s an "ExtraThin" source where things are now failing.

What might I look into to solve this?

Thanks for any tips or insights!