Hi,
I am using UE4Editor (4.22.3-7053642+++UE4+Release-4.22) on iMac 27" (OS X 10.14.5). Sometimes I use display’s “Scaled” mode as “Larger Text”, which looks like 1600 x 900.
In this mode Add New → Miscellaneous menu slightly doesn’t fit the screen and tries to decrease his height, than it it thinks that there is plenty of space and increases elements height but doesn’t fit. As result menu is flickering.
Similar issue: UE-22984