I have the same UI glitch under WIN10, but it is definitely NOT due to graphic card incompatibility.
Please test the following: under Cubase, start an instance of NI Kontakt, close it and start HALion. Then the glitches are gone! Obviously Kontakt intializes something related to the graphics interface, that HALion doesn’t. There must be faulty technical changes in H6 related to graphics, because H5 doesn’t have these glitches under the same WIN10 system.
I hope Steinberg hears me and can reproduce the described workaround to find the bug.