I got the same problem with Cura 3.4.x and 3.5.x with window 7 on my HP EliteBook laptop (Intel 520 graphic card). In fact my problem was not directly related to the graphic card, but to my setting of windows performance. (yes I prefer performance ratter than appearance) and one of my custom selection was causing the missing drop down menu in Cura
in windows setting ensure the following check box is selected.
Control Panel --> Performance Information and tools --> adjust visual effects --> Adjust for best appearance.
I didn't try a all custom selection to find out which one in particular was causing the missing drop down menu problem, but if somebody have time to figure out ...
