I am having the borders in 6.7.12 behaving strangely when I switch from a single setting to the ability to choose the borders independently.
Initially borders look like this:

When I switch to independent borders it sets the border to black (I don’t have black as a colour.)

If I try to change the colour it doesn;t allow me to set the same colour for both the base and the interaction.

I need to set the base, then the interaction, before I see the chain but if I go back to the base and click the chain it shows it has worked but I still get the interaction as black.
To have the interaction the same as the base I need to set both and can’t use the chain icon to have it set once for both.