Intermediates in variable font: broken for roman, not italic

Hello, I am running into a very odd issue.

I have a project with quite a few intermediate masters for some glyphs. Yes, I have them all set up so that the design space is quadratic.

The project has an italic axis. I exported one subset variable font with just the roman masters and one with just the italic masters (MyfontRoman-VAR, MyfontItalic-VAR). In the Italic variable font, everything interpolates fine. In the Roman variable font, however, I am getting bugs in all glyphs that use the glyphs containing intermediate masters as components (for example: a has intermediate masters, aacute interpolates with positioning bugs). They are jumping around horizontally. This does not happen in the italic.

Anything I can do to remedy this? I don’t expect that adding intermediate layers to all composites is the solution, as it works fine in the italic.