again i tried icarus and again it doesnt work nothing happens when equiped
even barebones modded with
fabric 1.12.2
architectury 3.4.9
clothconfig 6.1.48
fabric api 0.45.2
icarus 1.9
rei 7.1.361
trinkets 3.1.0
nothing happens , in f5 mode u can see the wings briefly blink like they want to open but nothing happens not in survival not in creative ( well.. double jumping puts u in creative flight)
i have no idea , no error no nothing in the log , not on single player , not on server. i dont know why it doesnt work

Put the wings on, leave the game, and re-enter and tell me if they're still on. Trinkets may be doing its garbage desync stuff

i just took out everything trinkets related ;_) and reinstalled them now it works ;-)