Hi, I hope, this platform is suitable for bug-reporting.
I came across a pretty critical bug, where the settings of Area Light inside the Cinema4D get set back when switching projects. I made a video with a simplified scene for you to reproduce: https://www.dropbox.com/s/eowd1m4bqkct8ko/HDRI-C4D-AreaLight-Switch-Project-Bug.mp4?dl=0
I've also attached the C4D-File for you to test the bug.
I lost quite lot of time due to this bug :( and needed a bit of nerve and guessing to set the correct values I've had before.
Cool, I found a workaround in the meanwhile.
When under "Edit Project in HDR Light Studio":
-> Click "Stop"
-> Switch the "Active Project"
-> Click "Start",
then it won't set the light settings back. Just one disadvantage with this workaround is, that it needs to restart the HDR Light Studio every time.