I love the new interface and especially the crispness of the high DPI mode but my VSTs are not scaling.
Is it because the VST creator is not following the VST standard?
My General tab in Preferences doesn’t even have a HiDPI mode option. 
That’s where the manual says it should be.
Anyone know a fix, or an alternate location?
I’m running 2160p, so should definitely have it.
For VST plugins to scale automatically, they should run via a VST host implemented as a separate non-DPI-aware executable, so that Windows could scale them. For example, Reaper allows to selectively run specific VST plugins in a separate process which results in proper scaling of non-DPI-aware plugins. If Cubase does not have such feature, VSTs will be small and unusable in HiDPI mode.
@flintoid - high DPI mode actually looks good to you? What am I doing wrong then? When I enable it, everything is just twice as big.
What OS does you have? Windows 7 or 8 is not supported for HighDPI, only Windows 10 (and Mac OS).
VST plugins are not run like that in Cubase 10, this Steinberg article states in Additional Notes:
“3rd party plug-ins need to support HiDPI on their own, else they may appear small and/or with a truncated user interface.”
My point is that it is technically possible to automatically scale non-DPI-aware VSTs in case of proper implementation. It is not necessary for VSTs to do scaling on their own. Whether Cubase does/will have proper implementation is up to Steinberg.
Yes, I understand your point that it’s technically possible.
I just mentioned what Steinberg stated, so that it’s obvious that they currently have chosen a different technique (causing these symptoms).
(They may have other technical reasons to do so, though).
That’s because the plugin interface is small in itself. It wasn’t designed for 4K monitors. Their high DPI mode seems to only turn off windows scaling and put their graphics back to normal size. It looks big and ok but a little blurry with normal windows scaling. Plugins like Omnisphere and the Roland Cloud plugins work fine with their plugin scaling approach. Halion seems to be the only plugin that suffers because the graphics in themselves are just too small.
High DPI mode in Halion 6 is not even close to being finished yet. Don’t know why they even put it in yet.