This is a difficult glitch to show through screenshots ...

This was a few (2 or 3 I think) tactical rounds after casting Tame.  Notice there's no cooldown timer countdown at all.

In another tactical combat, I get the countdown, and it proceeds normally until I get to 6 turns left on cooldown, at which point it continues to report 6 turns left on cooldown for four more of the caster's tactical rounds (in which I skip tactical rounds with the space bar)  until she (the one with Tame) casts Heal, after which the cooldown does finally update to 2 turns left on cooldown, but then does not update her next tactical round (again I had skipped the rounds awaiting the cooldown to complete) so report 2 turns left on cooldown again even when there was only one remaining turn.  Oddly enough, on the turn the cooldown completed, the Tame spell still reported 2 turns left on cooldown even though the spell, as can be seen below, was enabled and ready to cast: