Windows 10 / 24.08.29
I have a clip on the timeline with a quick Speed:Forward Only effect of 1 → 0.5x → 1x.
Copy this clip and paste it somewhere else in the timeline.
The Speed filter appears active and still has the already set time keyframes.
Hit play to preview the time effect but the video is always at normal speed even though in the filter UI the speed appears to change and the duration also appears to be affected (=if I set speed to 10 the video simply ends quickly but without speeding up).