When you summon your maximum number of Wolves at once, and then summon another companion, the number of Wolves correctly reduces by 1. However, this is not the case if you’re using the Summon Crow ability alongside the node that allows you to summon just 1 of it. The summon simply fails and the cooldown begins despite not having a crow.
What you need to do is un-summon the Wolves (by placing another skill in its place), summoning the Crow, and then re-summoning the Wolves to your companion limit. It gets better. When you leave to a new zone, the singular Crow disappears and the Wolves are summoned up to the limit again. Then you have to un-summon the Wolves, summon the Crow, and re-summon the Wolves again. Every time you enter a new zone.
I think this is clearly a bug and something that needs to fix if you want to do max Wolves + 1 Crow, as it’s a mess right now.