I needed to change my stackup which was originally something like:
to a modified stackup
I went to Board Setup | Board Editor Layers, and made the adjustments.
The Board Setup | Physical Stackup now looks the same as in the Board Editor Layer. OK out of that.
Then, in the PCB Editor window under Appearance | Layers-tab, I have the layers listed according to the modified Physical Stackup (good). But, upon inspection of the board:
SIG1 the first layer is as expected
GND1 the second layer is as expected
SIG2 however does not have SIG2 signals on it, instead it is the original PWR layer.
So instead of KiCad keeping SIG2 signals on a layer named SIG2, it just kept everything in the same layer order as the original stackup. Is this how it is supposed to work?
What is the best way to migrate my otherwise routed board signals to their correct layer without mistakes?
If I understand you correctly, you only renamed some layers, but nothing on the PCB actually changed.
If you want to change the layer order on the PCB, you have to: PCB Editor / Edit / Swap Layers ….
That is correct. I only renamed the inner layers and moved some plane layers. “Swap Layers” did the trick, then I just had to modify the layer colour to make everything perfect.