Rendering ranges of sample chunks only works reliably for us after Blender commit 7744203b7fde35a074faf232dda3595b78c5f14c (Tue Jan 29 18:08:12 2019 +0100).
Rendering ranges of sample chunks only works reliably for us after Blender commit 7744203b7fde35a074faf232dda3595b78c5f14c (Tue Jan 29 18:08:12 2019 +0100).