I’m currently experimenting with optical sizing for an icon font (with Glyphs 2.6.1). Because optical sizing is most important for just a couple icons, I’ve tried using
Virtual Master. It appears to work in Firefox, but Chrome and Safari both refuse to render the icons that have optical size set on them with CSS.
Any icon without these axes set still works.
font-variation-settings below 100 (the minimum for the axis) for optical size renders the icons as optical size 100. But going back up to 100 causes them to fail to render again. Going above 200 (the axis max) doesn’t trigger a successful render.
Edit 2 This is in Chrome 73.0.3683.75 and Safari 12.0.3.