OP, pull the tweeter out and give it a visual. Then ohm it out. Maybe they are blown. Smell funny? Like electrical burn.. Is there no resistance or maxed out? Disconnect the driver to check, ay..
After that, it’s wire or crossover..(you changed the resistor).
You’re not running some weird main cable are you? With a hi pass filter in it are you? Like a Transparent?
Some of those cables will cause all kinds of problems, like amp oscillation.. Depends on the amp..
You ran a new piece of cable just to check? CHEAP zip cord will work fine.. LOL may be the cure..
Happy hunting..