so anyway i finally thought i had this thing dialed in and then i watched the blackbox footage and there are these high frequency oscillations on roll that just will not quit. tried lowering P on roll, that helped a tiny bit but then the quad just feels mushy and slow to respond. bumped D back up and the oscillations came back worse.

its a 5inch on 4s, running 2207 motors, props are HQ 5.1x3x3 which i know some people have opinions about. the filters i honestly havent touched much because i was trying to sort out PID first but maybe thats the problem. RPM filter is on, the motor mags are in betaflight. i dunno. i feel like ive been chasing my tail for like three evenings now and im starting to think theres something physically wrong but the motors sound fine and the frame is tight.

anyone been down this road

check your motor screws first, seriously. i spent like a week convinced i had a software problem once and it turned out one motor was just ever so slightly loose and causing the whole thing to resonate weird. also are your props balanced? HQ props are usually decent but ive gotten bad batches before.

if its not mechanical then yeah look at your filtering before keep hammering PIDs. if RPM filter is set up right it should be doing a lot of the heavy lifting. what does your gyro trace look like in blackbox compared to the setpoint, is it tracking at all or is it just noise everywhere

D term oscillations on roll specifically usually means either a mechanical resonance issue or your D is actually too low not too high - sounds backwards but its true, D that's too low can't damp the oscillation fast enough so it just keeps ringing. theres a good video by Joshua Bardwell on blackbox analysis that covers exactly this, might be worth sitting through even if you think you know betaflight already. also what fc are you on and whats your gyro lowpass set to, if its at like 100hz thats probably leaving a lot of noise through