adi,xo-disable-use-ext-refclk-enable sets bit-4 in Reg 0x009 (Clock Enable).
My understanding is that this is the only bit needed to switch the mux to EXT REF Clock, instead of XO into XTAL.
I also have a board that uses EXT Clock , and it also works if the mux is set the other way.
But this doesn’t surprise me.
Greetings,
Michael