Thanks, Pete, for the files.
I have tested any possible combination, in C4D, Ae as well as Fusion. After many hours, I think I can say with certainty that the Multilayer OpenEXR in S22 has a problem.
If you open the file in the picture viewer and set up the blend modes for your file, perhaps as simple as GI+, Spec+, Shadows*, Diffuse [BG]. It will show much differently than Background-RGB.
Given that the Reflection pass is not included, one could think that would do the trick, but it is far away from lifting all the values. So, for now, Multilayer OpenEXR in Ae is a no go.
If I render out the scene as I typically suggest, in 32bit/channel and float, all is fine. I use 32bit/channel/float always, and yes, files are larger, but since I like data channels as well, they are more comfortable in 32b/c/f.
The 32b/c/f, exr: Multilayer as well as single-layer show no problems here. The single layer is working in OpenEXR and 16bit/channel/float as well.
A 32b/channel/float PSD file works fine here. (Not the most efficient, but no other problems.
Single-layer renderings allow for the “aec” file to be written, and those set up the comp all ready for you.)
I have to file a report. Sorry about the 16bit/channel trouble.
All the best