uniwidth/multiplexed fonts extend in Illustrator

A font of mine is uniwidth/duplexed and keeps its width in inDesign and Dinamo’s Font Gauntlet when changing the weight of the VAR.ttf.

In Illustrator however, the text ‘extends’ when adding weight. Visualized: The last letter on a line is standing further right than before. The other way around it also contracts when lowering the weight, obviously.

I went on and found the same behavior in other VAR fonts (right in InDesign, wrong in Illustrator), but also ones that don’t have the issue. My Illustrator version is up to date, and the bug was also in the previous version.

Please fix this, thank you.

Please have a look at that, type designer make uniwidth fonts exactly for the reason that they KEEP their width when changing its weight.

Best,
Daniel