Host hangs on reboot/shutdown with ISCSI storage attached.

Hi guys, i have a problem. here's what i did so far.

1. Installed Xenserver 7.2 on 3 new servers (1 Dell and 2 Supermicro).
2. Installed the updates on all server.
3. Created a Pool and added the 3 servers.
4. Created new ISCSI SR (for heartbeat lun).
5. Configured HA.

Basically what i want to achieve is a 3 host pool with ha. Problem is whenever i reboot the server it hangs on the "Reached target shutdown" part on all 3 servers in the pool, i have to hard reset everytime. But if i dettach the ISCSI SR, it reboots fine. I redo all the above procedures above and still the same. Im now trying to install 7.1 and see if it produces the same. Hope you can help me with this. Thanks.