What is your operating system?
What is your Shotcut version (see Help > About Shotcut)? Is it 32-bit? 21.09.20 64 bit
Can you repeat the problem? If so, what are the steps?
Import a clip, change its speed in properties, drag it elsewhere on the timeline and it turns out black.
(Please be specific and use the names as seen in Shotcut, preferably English. Include a screenshot or screen recording if you can. Also, you can attach logs from either View > Application Log or right-click a job and choose View Log.)
I found a work-around for this - by opening another video timeline I could edit the videos in that timeline and if I decided I needed to move it I could drag it to the one below without issues.