Mac Studio Max with LG 27UK850-W

I have a brand new Mac Studio M1 Max base model and I've connected two LG 27UK850-W

4k displays via USB-C directly to the machine. All works great until I leave the machine overnight and it goes to sleep. When I wake it up, the displays come on and shows the last contents before sleep and it's stuck there. The mouse moves, but it appears the displays aren't updating even if I blind launch an app. If I power off both displays, then power them on again, it will return to operation after a brief pause. I've read some other questions similar to this but my screen isn't black. It actually has the desktop image, it just won't update. Is it really OK just to turn off the OS sleep? This works perfectly well on my 2021 MacBook Pro (Intel) with the same displays connected via a CalDigit TB4 Hub.