Vero 4K+ HDMI issue

I’ve encountered a very strange problem with my LG OLED55CX. I connected my Vero 4K+ last weekend and apart from a small problem running 4K video above 24hz (now resolved) it has been performing well. Yesterday my Sonos beam, which is connected to my LG tv thru the eArc HDMI, stopped working. After a bit of investigation it turns out that somehow the Vero 4K is stopping the eArc on my tv outputting to the Sonos.
I’ve connected different devices to the HDMI port I use for the Vero, but these don’t create the same issue.
Has anyone encountered anything like this ? Any ideas what is going on ?

Apologies, I see this has already been discussed in another thread.