[Wowfunhappy]

I don't know what you're seeing but the retina scaling options don't appear on any non-Apple display I've ever used. (Unless I hack the kexts.)

[dont__panic]

You generally have to use the right equipment -- using mini displayport or thunderbolt 3 instead of HDMI, depending on the generation. It's definitely finicky (much like getting guaranteed 4k60 output, especially through a dock)

[Wowfunhappy]

Ah, maybe that's the key, I almost exclusively use hdmi.

[Aloha]

Works for me, I'm using two fairly new dell 4K screens, as far as I know it works on any hidpi display

[tonyedgecombe]

It does for me on both LG and Dell monitors.