UI: Setting `C` with one channel but data having multiple channels

[jdeschamps]

Question

In the UI, what happens when user set axes with C and one channel but the data has multiple channels?

Currently, the would have to go into the advanced settings and set the number of channels manually. There is no message or feedback that would tell them where to find these settings, and that they have to set it.

E.g. we could have a pop up when people add C axis, to warn them to set the advanced settings.