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What is your Shotcut version (see Help > About Shotcut)? Is it 32-bit?
Can you repeat the problem? If so, what are the steps?
(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.)
Working on a project that has multiple video tracks, with an track for images on top for some text overlays - which were PNG’s with transparent backgrounds. I watched it over and over while editing and the transparency worked perfectly.
I added my music audio track (below the video tracks) and transparency on my images still worked fine. Then I added my voiceover audio track (and all the video and the image tracks were locked at this point) and suddenly the transparent background on my images track is broken - they are completely black except for their text portion and so cover the video entirely. Basically they were working fine and the track was locked and then suddenly, they were not working…