I guess I have figured out the reason why it's not working, please see below configs I did on the GE4/1/0 and GE4/1/1.
Interface-profile switching-profile TRUNK
Switchport-mode trunk
Trunk allowed vlan all
Exit
Interface-profile lacp-profile LACP_23
Group-id 23
Mode active
exit
Interface-group gigabitethernet Uplink
Apply-to 4/1/0,4/1/1
Switching-profile TRUNK
Lacp-profile LACP_23
Exit
I firstly configured the 4/1/0 and 4/1/1 as the trunk port which is a MUST to change the default switching-profile to the TRUNK (named by myself) swithcing-profile, and this causes the LACP profile not able to be applied on these two ports.
I tried the exactly same configuration on another switch WITHOUT inroducing the trunk port, and the LACP is working fine.
The problem now is that, for my Arista MLAG setup, I must have both TRUNK + LACP configuration on these two uplink ports, and it looks like it's not possible to be done on the aruba switch, please advise any solution for this?