So I'm playing in 1280x1024[4:3] and on certain research projects the "research" button is not visible.
This only occurs when "UI scale" is set to "System Default".
Like so:
System Default
"System default" setting. As you can see the button is gone despite research being "available".
Another research project:
And here it is with Custom scale set to 80%:
Custom Scale
As you can see the button is now visible, although barely.
I'm pretty sure this wouldn't occur if only I could play at higher resolution