Receiving black frames with Intensity Pro 4K

Hello!

I'm making videos with my own C# program. When I was using Intensity everything worked fine, but after I switched to Intensity Pro 4K I started to receive black frames, the audio was still fine though. The environments are the same: Win10, 1080p24, 8bitYUV. I tried couple different versions of desktop video but it didn't help. Media Express works fine by the way. Anyone got any ideas?

Thanks!
Zicheng Wang

Bump...still not solved. I noticed that wrong input formats would cause black frames, but I'm pretty sure that my input format and input display mode are both 1080p24.