Newbie: Combing trouble with exported video [Solved]

Hi folks! I'm new to DaVinci Resolve, but I've been working with digital video for years.

I have 1080p30 h264 source from a webcam. To test out Resolve, I did a simple chroma key. (Which works amazingly well!) But when I export, things go weird.

Everything I export, any codec with any settings, comes out with combing as if it were a bad interlaced conversion. I'm quite positive my source is progressive. I've been at this for hours and I'm at my wits end. Does anyone know what's up?

I'm on DaVinci Resolve 15.0.0B.065, Windows 10 1803, AMD Radeon HD 5700 GPU, AMD FX-4100 Quad 3.6ghz CPU.

Thanks so much!

[Peter Chamberlain]

Try rendering a few seconds in dpx format and let us know what you see.

Ah, what a night's sleep will do for one!

I had my timeline set for 28 FPS. And it's been so long since I've had to think about interlacing that I didn't realize that the "(3:2)" in the 30 FPS export I was choosing was 3:2 pull down! Hence, combing.

I set my timeline for 30 FPS and all is well.

Thanks!