I have always run the Scarlett at the max buffer size of 1024 without issues. With Dorico 4, I am now getting periodic clicks (about once per second) at that setting. If I set it to any lower value (say 512) there are no clicks and no other adverse results. I am just mentioning this in case others see a similar problem.
I went back to Dorico 3.5 and created a new project and it has no clicks even at 1024.
I created the same new project at Dorico 4 and it always get the clicks at 1024.
This is not necessarily a bug, and has an easy work-around. But it seems counter-intuitive that the clicks would occur on the largest buffer size. I would have expected clicks and dropouts if the buffer was too small.