This is a slightly involved bug.
1. First, create a title clip with text and create a new gradient for this text in titler.
2. Next, add the title clip to the timeline.
3. Now add this timeline title clip to your library bin.
4. Then start a new Kdenlive project.
5. Add the title library clip to your project.
6. Draw the MLT library clip into the timeline, then expand it.
7. Edit the title clip.

While the title clip both in the project bin/clip monitor and timeline correctly shows the text with gradient, the title editor doesn't show the text with the gradient. Instead, the text is rendered black. In the title editor you see that the gradient is there and selected. However, the titler does not correctly pick up the gradient information.