And likewise.
It is a mystery to me why some Euphorbias are so reluctant to root, and others take off. It seems to depend on the plant and sometimes on the season. Presumably individual Euphorbias are different that way. Usually I try to forget about cuttings for a while but when it starts taking more than a year then I start to doubt if it's ever going to happen. No doubt there are tricks and tweaks that I haven't tried.
Even the easiest Euphorbia to start from cuttings here (E. ingens.... stick a cutting in the ground and you cannot fail) tends to skip a growing season while it sorts out the situation below ground.