It seems that you are performing noncollinear magnetic calculations (nspin=4) which is not supported in EPW.
Currently, EPW only supports (1) spin unpolarized and (2) nonmagnetic spin-orbit calculations.
So I need to modify the scf.in file in phonons and set noncolin=.true., lspinorb=.true. and starting_magnetization=0. And then redo the phonon calculation?
In addition, I would like to ask you to use the most recent version of QE & EPW, for instance, QE v7.1 with EPW v5.5 which can be downloaded at https://gitlab.com/QEF/q-e/-/releases .
PS) If you don't explicitly specify starting_magnetization, starting_magnetization is 0 in default, leading to the non-magnetic calculation.