Since i couldn't find a mineshaft in survival, i tried to go on a creative new world. And i found that the mineshafts existed, but like, it was just an little alley with a tnt minecart. That was all. Like it was really tiny.
I tried to find a new one (after all it could have been bad luck), and i found no mineshaft where i teleported.
Then i checked the mod config and saw the generation y and thought that maybe the caves generation were overriding the mineshaft.
So i tried to desactivate the better caves mod, and guess what ? It worked. It's probably the same on the forge version since i couldn't find any mineshaft either with only your mods on. Didn't tested it tho.