LUT error in connectome viewing tool

Dear MRtrix3 community and developers,

I am not able to use this LUT2.txt in the connectome viewer. It gives the following error.

The only difference I am able to pin point between a working example LUT1.txt (generated from labelconvert of mrtrix3) and LUT2.txt (generated using R) is that subsets of nodes are grouped, and each group is mapped to a same color in LUT2.txt. Could that be the reason?

Could you kindly help me resolve this? Thank you for your help and advice!

Best regards,

P.S. I am also not sure why the third column is not an 8bit integer as shown in the screenshot above. I didn’t treat that column differently when writing from R! Would be happy to share my R code if that could help. I thought the LUT files might offer a good starting point.