Some ZWJ sequences don't display

[nullbasis]

Using the most recent version, 13.0.1, on Ubuntu 20.04. This issue persists in three different browsers (SeaMonkey, Vivaldi, and Firefox, all of them up to date), but presents slightly differently in each browser.

SeaMonkey:

Firefox:

Vivaldi:

I don't know if I need to change a setting in my browser(s) or if it's a limitation of my OS or if the problem is with the font. Help?

[13rac1]

Odd. This will require some debugging. I'm not sure if the problem is the font or the build process. I suspect it may be due to missing ZWJ sequences in the svg file names