Smoothing Time not working

[HAWK77766]

I have the Pimoroni Plasma 2040 and use it in multi-segment mode for 328 (2x164) LEDs. Everything works fine except there is almost no smoothing. If I turn smoothing off there is some flickering so smoothing does something but there is no difference when set to 25ms or 5000ms. The LEDs change too fast when the content is erratic which is distracting and tiresome.
Setting it to 20Hz or my max benchmarked 143hz (7ms) refresh rate does not change anything so that is not the problem. I use HyperHDR software screencapture.