Add Motion Blur to Drone Footage

I'm playing with some 4K footage inside a HD timeline. The shutter speed goes pretty high with the drone on a sunny day without ND filters and there is a certain jerkiness in the image. I am trying to add some motion blur to the images inside Resolve 15, but the controls just don't see to do anything.
I tried with some other shots from the drone: same thing. Nothing happens.

I switched to another project that has Sony FS-7 XAVC-I footage in it and there I can see an effect immediately, when I raise the Motion Blur level.

Does Motion Blur not work with certain codecs or bit-depth footage?

I'm at a loss here and would appreciate an explanation or hint what I'm doing wrong.

Cheers

Florian

Being a temporal effect, motion blur can generate quite some load for your GPU. Which one do you have?

I know, that that is a processing intensive operation, but it works on other footage. I got a Radeon Pro Vega 64 with 16GB VRAM.

Well, that should suffice!
Can you publish a short clip for us to test, so we can check if it’s a bug specific to the software or to the clip?

Try to render out a clip, or at least wait for the Smart Cache to build—does it show up then?

Maybe it's a thing that Resolve won't render certain effects on h.264/h.265 codecs (CPU intensive Long GOP) in the timeline, but only at render time?

I tried to create "Optimized Media" inside Resolve to see if it's a codec issue and Resolve 15 B5 crashed immediately. So I transcoded the media from the drone to ProRes and voilá the Motion Blur is there! So it seems to be a codec issue.
The footage has been recorded by a DJI Mavic Air Drone in 4K at 29.97fps, if a DEV is interested. Not sure why Resolve crashes when it tries to transcode the footage.

R15B6 seems to have solved the issue. I can create optimised media from Mavic Air footage now without Resolve crashing and Motion Blur works now on Mavic Air footage without transcoding.