Hi @k99 !
This is a known Nuke bug (don’t know the issue number, but you can find it in their bugtracker) and there is a (ridiculous) workaround for it. Just add this to a studio wide init.py file ( I hope you have one) :
def set_ocio_color_management():
if nuke.Root()['colorManagement'].value() == 'Nuke':
nuke.Root()['colorManagement'].setValue('OCIO')
# Simply switching to "OCIO" can leave the "Thumbnail" and "MonitorOut" settings
# in the on the root node in an old state. To force an update on these, we
# need to switch to "Nuke" and back to "OCIO" again.
nuke.Root()['colorManagement'].setValue('Nuke')
nuke.Root()['colorManagement'].setValue('OCIO')
nuke.addOnCreate(set_ocio_color_management, nodeClass='Root')
Hope they address that in future releases.
Cheers,
Fabian