ZBrushCentral

When I use multinsert brush some of the recently added meshes disappear

When I insert several meshes quickly they do appears. But next time I insert one more thing in a bit of time, just a second after actually, a few of recently added meshes disappear.
So I have to wait a second after eash insert to keep things. Is it a bug of feature? How can I fix it?

look here…

Could you explain a bit more please. I am not sure I understand.