I want to have a chroma keyed transition to make it look clean but I tried doing chroma key on shot cut and adding a transparent image but just adds a black screen when it starts and ends not the transparent background.
You need to have a new track with opaque image or video below the chroma keyed track, because shotcut does not support alpha while exporting and doing playback, It is hard to export the video with an alpha for now.
I had to search what a stinger transition is. From the examples I found, maybe the method I explain in the video bellow will work for you. It shows how to export videos with transparencies.
(Some examples are shown at 7:13)