The recipe for glass is unavailable when using AAI, Crushing Industry, K2SO, and K2SO Tweaks together.
Examining the "Sand Processing" entry in the tech tree shows that it doesn't unlock anything. Neither does the "Glass Processing" entry.
This is NOT caused by K2SO Tweaks, but it seems like a good place to fix it.

elevated-rails 2.0.69
quality 2.0.69
space-age 2.0.69
aai-industry 0.6.13
crushing-industry 0.4.13
fsdl 0.2.2
flib 0.16.3
Krastorio2-spaced-out 1.4.26
Krastorio2Assets 2.0.3
Krastorio2Inserters 1.1.6
Krastorio2MenuSimulations 2.0.2
multispoil 2.1.2
nulls-k2so-tweaks 1.8.1
PlanetsLib 1.13.6

Looks like this is still the case, has anyone found and/or made a fix?

Going back to an older version of the crushing-industry.lua file (Reverting the oct 4 commit regarding the k2 glass recipe) fixed the issue.

Edit: Not sure if it's because it was changed in an ongoing savefile or if it's something else, but the recipe is now showing up as
Uknown Key: "recipe-name.kr-glass"