I'm new to this, so I've probably just missed something obvious.

I'm using FontForge v20201107 on Ubuntu. The font I'm working on "just works" on Linux and MacOS, but on Windows, the kerning does not work. The font installs and the glyphs look right, but there is no kerning.

In the generate options, I've checked hints, flex hints, truetype hints, PS glyph names, OpenType, Windows-compatible kern, and prefer native kerning. That last does not seem to make any difference.

* For the Regular style, Font Validator gives me E2101 "There are undefined bits set in fsSelection field" Bit(s) 7

* For Italic, it also gives "E1318 The macStyle italic bit is set, but the
post table italic angle is zero", and "E2310 The italicAngle is zero, but the head.macStyle italic bit is set".

So the question is; how do I make the kerning work on Windows?

https://github.com/fontforge/fontforge/issues/4283

I was right; I missed something obvious. I used WordPad to test the kerning on Windows, but it seems WordPad does not support kerning. I generally only use Windows for gaming, which is why I didn't know. Then I opened the same file in Word, and as far as I can tell, the kerning works the way it was meant to do.

I had no idea there were text editors that do not support kerning.

Problem solved, though.

< WordPad will, however, happily kern if you copy-paste e.g. a paragraph from Word after enabling kerning for the font size it uses.>

https://github.com/fontforge/fontforge/issues/3272

When I was making my only alphabet font which isn't monospaced, I created an MS Word doc and typed the 676 letter pairs, (AA - ZZ). I then selected the most recent version of the unfinished font for the entire document, and looked to see if the kerning looked correct at different point sizes. That word doc can be reused for any installed font.