Track colour stays with track number?

Odd thing happened today.

I had a small test session up;

Number = channel position

1 mono audio channel

2 stereo audio channel

3 aux channel

4 master channel



All had their default colours.

When I dragged the master channel to position 3 it took the aux channel colour & the aux channel ( now at position 4 ) took the master channel colour.

Eh ?

Tried a restart. … same.

Is it a pref ?