Can Linux have problems with kerning tables?

[Ultra]

I was working on the kerning pair table when suddenly the new entries I was making didn't have any effect. This was on a Ubuntu 16.04. I tried everything such as purging the font file and trying different clients--they all behaved the same way: new kerning pairs don't work. The funny thing is I've tried it on another Ubuntu 16.04 and a Ubuntu 14.04 and they work there. I wonder if I've done something to make the font unstable such that it will randomly work or not work.
Here's a sample of a kerning that works.

and here's one that doesn't work:

The font file I generate is a TTF. Is there a way I can post the sfd? I expect that would give insight into the problem

[Ultra]

Actually, the problem doesn't seem to be the system using the font file, but the system generating the font file. The font files that one system generates is bad, but the other two system generate good font files. Must be a bug in one of the FontForges or, more likely, one of the dependencies.
Here, I figured out how I can link non-image files: the good, the bad and the template. Where do I submit bug reports?