I have a serious problem with TR, and this happens to me on many scenes…
When I try to use TR (in any mode - manual\automatic\arbitrated) I get very very dark renders, and in arbitrated mode I get wrong colors on some objects - Any idea why ?
Just as a test, if you are using photographic exposure overwritten by a corona camer tag, try to swith to photographic exposure in the main render settings also. Don’t ask why, for me it worked