Of course, after "on transition: unmute all", the choice for "on transition : Solo" should be there again in the menu.
But it's quite irrelevant if the channel already is in a 'Solo' state.
The same would be, if a channel already is muted, to have a choice of "on transition: mute".
But in that case it's done correctly by changing the choice in the menu into "on transition: unmute".
Your reaction triggered me to check this again, and now I understand why this solo-option is there.
Because, if a channel is in solo-state, and one opens the context menu, there's no detection whether this is
the only enabled channel. So if 3 other channels are enabled too, it would give the same menu.
And in that case, the "on transition : Solo" is a valid option of course.