There is no sort button on the gui of the chests from better storage
running latest versions of both mods.

is there any way to get this working myself?

I believe it was changed so that other mods have to hook into InvTweaks' API to enable sorting due to previous issues with unsupported modded inventories.

It should work on dev versions (and possibly release + recent better storage), but I can't make it magically work when the people making mods decide to rename things. This is why the API exists though, so I don't have to constantly keep up with every semi-popular mod and every time they decide to rename their classes.

thank you kindly