I am using Windows 10 on a Dell I7 laptop
After updating OpenLP from v 2.4.6 to v3.0.2, OBS showed a black screen when capturing the OpenLP output display.
(I appreciate this is the same as point 2 in 3.0.2 Black screen on Show Desktop — OpenLP Forums)
I found that if I click the mouse in the output display, it does appear in OBS but after about 10 seconds, the text disappears leaving only the theme.
I have returned to v2.4.6. Fortunately I had a recent Ghost image of the laptop.