Just making sure this is clear, especially for others who will read this thread.
The corrections would need to be done on the ECP's Source tab if done in another sequence. Anything done on the Source tab, the left one at top of ECP, is applied to the clip in the bin and any use of that clip in the project.
Effects applied to the Timeline tab of the ECP, the right tab, only go to the clip on that sequence.
So, are you applying the color to the Source tab of the ECP?
Personally, the way I handle this is make a sequence of the clips in the multicam. Do my normal neutralizing/shotmatching routine. Then for each clip, "cut" the Lumetri from the Timeline tab and past it on the Source tab. Ctrl/Cmd-X to cut, Ctrl/Cmd-V to paste.
I have the same problem, I think. I'm attaching screen shots to show what is happening. I also have a MC sequence where I correct each camera and grade them all together. That final grade is not showing when I go to the Multicam Sequence for cutting.
Already tried closing and reopening both the project and Premiere. Didn't work.