HA Connection lost after change Management IP address

Hi guy,

I have a problem after change mgmt IP. It's HA connection lost (result in IP conflict and downtime)

I have to change management IP address of BIG-IP redundant pair. But when we change it, HA connection lost and it's become active/active which cause us a downtime of application.

I have configsync and failover unicast IP is 2.2.2.2 (peer is 2.2.2.1) which connect directly with each other.

How can this occur? Is really changing mgmt IP of the box cause it HA connection lost?

Note. In v. 10.2.4 , we can change it just fine. Now we currently Running v.11.4.1 HF5