Pulsing Envelope

[Bis]

I'm playing as Pontus in the Great Mithridates War. Pontus' envelope is white and the tooltip say he's activated. However, the envelope pulses and he won't move. I've declared war and have run several turns. What's going on? Thanks.

[Ebbingford]

Check if there are any locked units in his stack.

[Bis]

Found them. Thanks.