Thanks for your help.
I loaded them one by one by loading one output channel at the time into a empty project, just to test each channel and see if I could isolate the fault to any specific channels. Fir Designer pushed all three channels at the same time, but I only put in settings in one or two of them to test my design.
I figured out the sample rate as you describe, got some error messages on them as well in the beginning.
If you don’t mind, I’ll mail my design so you can have a look at it 🙂