Blur: Gaussian & Exponential Clash With Preview Scaling

Depending on the resolution for preview scaling you pick and the resolution of the file itself, both Blur: Gaussian & Exponential will produce a black screen when cranked up to 100%. You get a black screen:

If you have a 1080p video and use 720 preview scaling.
If you have a 720p video and use 540 preview scaling.
If you have a 480p video and use 360 preview scaling.

I didn’t get black screens when using 4K video and preview scaling. However, if you use specifically 4K UHD video with preview scaling off, apply Gaussian and crank it up to 100% visual glitches are produced.

There are no black screens with any preview scaling nor any visual glitches with either of the Blur filters when using DCI 4K video.