I always put a lot of effect on my layer (between 10 and 15) and sometimes use them together. I can't say if it turns black after a specific manipulation. But I am pretty sure it happens when I am using an effect on my loop. And for me, everything is working well inside my composition.
yes it comes back alone after 3-5 seconds with the same loop I was playing before. Even if I click on another loop, hoping that the black disappear, nothing happens and I have to wait.
Is there a maximal number of effects in one layer you recommend ?