I created a lead-emitter and a ribbon-emitter. Only when I set the Spawn-Rate to “0”, everything works fine. When it is set to a value above “0” the ribbons have a buggy behavior like you can see in the GIF. Even when I disable the Spawn-Module, the bug exists (even though I expected that the Spawn-Rate is really ignored at that point).
The reason why I tried to disable the Spawn-Module is the official documentation, where this is shown (scroll down for the 2nd picture): 2.5 - Ribbon Trails Streaming from Other Particles | Unreal Engine Documentation