Since long time I'm using a 27" and a 4k display. Every other software can handle this (I'm using more than 20 softwares). Only Autodesk Maya and 3dsMax are not able to handle this.
What happens:
Menu items (drop down menus) open outside of screen space (= invisible) or with extreme high scale and cropped at completely wrong position - as soon as any panel is placed the second screen.
I had that discussion already at the 3dsMax section. There is no solution, it just took hours and hours of testing (environment variables, common settings, display settings...).
I have always to minimize or close all windows on the 4k screen.
cropped menu, not readable. others were even invisiblecropped menu, even not responsive for mouse. unusable
Maybe maybe this seems worth to have a look after years... I know other have reported this as well.