Operating system: Windows 10 20H2
Graphics card: RTX 3090 FE
Broken: from 2.91 to the latest 2.93.0 beta version
Worked: Never tried it before so do not know
Short description of error
When linking a collection with lights from another blender file, Viewport Cycles won't update said lights position if you move the collection around, only if you leave viewport render and come back. No problem in Eevee. Very impractical for animation.
Exact steps for others to reproduce the error
From base startup:
1 • Just create the base file with the default cube and default light, it's probably already there
2 • Bring the light closer to the cube to see the glitch easier later, or make the cube bigger to bring it closer to the light.
3 • Save as file1.blend and create another file where you'll delete the base cube/light for a way cleaner test
4 • File > link > file1.blend > collection > collection, keep all the checkboxes checked in the pop up, you know have the base collection of file1.blend as a linked collection.
5 • Go to Render Properties and change the engine to Cycles, then switch to rendered viewport (shortcut Z+8), everything should look nominal with the cube correctly lit from its point light.
6 • Move the linked collection away, observe as the light emitted still comes from the old position although the light object from the collection moves along with the cube.
7 • Get back to Materiel preview (shortcut Z+2), and switch back to viewport render (shortcut Z+8), cycle now has updated the light correctly
8 • Moving the cube again will yield the same problem