I got hit by Crush about 10 times. Even the very first hit lowered my ATK. Any time my DEF did not get lowered, my ATK was lowered instead in the F1 window. This is exactly what the skill description says.
If you are not experiencing this, my only guess is that the attribute could be altering things. I am not sure if the person that hit me with it had the attribute or not, so you could test with or without it to see.
Attribute has to be ON, attribute effect is the topic after-all 
. Youâve been dancing on the wrong music all along, which in our case the attribute is ON and attack reduction doesnât proc, thus with a conclusion that it (attribute) âdoesnât workâ.
ATK reduction is a core functionality of Crush. The attribute just amplifies this and adds the equipment penalty. Your claim is that the attribute has been âbroken since foreverâ, but itâs working just fine. There may be a bug where turning ON the attribute makes the ATK reduction stop working, but thatâs not what you said, and something I have not personally tested.
I only have two things about the current TBL: Use Linker and Thauma in the build, stay extraordinarily tough and kill any enemy with any weapon and ability to use. And IMC is shitting for it!
It really is sad how IMC deals with problems related to TBL. To get well on TBL: Play ThaumaLinker with any other combination, make full con and be happy, or use mount character and see the enemies suffering to try to hit some skill target in you.