I think it is because pl->act_link_an_mode stays at MLO_AN_INBAND, but
it needs to be set to MLO_AN_PHY, so that only the phy determines the
link state:

phylink_resolve() {
    ...
	} else if (pl->act_link_an_mode == MLO_AN_PHY) {
		link_state = pl->phy_state;
    ...
}

phylink tries to determine the whole chain is up. As Russell says, it
could be the PCS has not got sync with the PHY for some reason. So
even if you ignore the PCS state, it might not work. This is actually
a useful pieces of information. Does the link actually work end to end
if you only look at the media state? If it does, that would indicate
the PCS is maybe missing an interrupt, or needs polling for change in
state.

	Andrew