Just checked, no differences.
Looking better it seems no eGPU work neither in the Sharing mode (FCPX have a LITTLE rendering with internal GPU, the biggest part is done by cpu I suppose)
I got the 10.4.8 (and 10.4.7) and I am furious!
FCPX slow down with my system (13" Macbook Pro 2016, egpu Rx 580)
It is impossible to cut in a 4k timeline, it's sluggish,
I have to create proxies..
It wasn't like that in the 10.4.6,
which work using the egpu even in Play mode,
now the external card is used ONLY for render and export!!