mkschmitty
I tried this and it doesn't appear to make a difference.
As per your suggestion, here's the new rule list in our config:
file_rules:
- !<Rule> {name: OpenEXR, extension: "exr", pattern: "*", colorspace: ACEScg}
- !<Rule> {name: Default, colorspace: ACEScg}
When the my scene is reloaded (after restarting Houdini), the EXR texture appears different when I switch between Signature = Color, vs. Signature = Vector 3. I would expect them to be the same. (The texture looks correct when I switch to Signature = Vector 3)
Also, changing the Default rule colorspace to ACES2065-1 or "default" makes not difference.
It doesn't do that for me. A exr image loaded with mtlx image set to color or vector3 looks the same either way when using a config tagging exr as ACEScg and a working space of ACEScg. Are you sure you saved the changes to the config and that Houdini is picking it up? It's pretty easy to save the config from the OCIO editor while Houdini is looking somewhere else.