sh sharing detail
Load Sharing Monitor
Config Current Agg Min Ld Share Dist Ld Share Agg Link Link Up
Master Master Control Active Algorithm Flags Group Mbr State Transitions
1:2 1:2 Static 1 L2 A 1:2 Y A 5
L2 3:48 - R 1
you should verify that the links are connected the way you want. You could enable LLDP on both the Cisco and Extreme switches, enable just one of the links, and then verify LLDP neighbors on both switches, and verify LACP information received on both switches.
Then you disable this port again and enable the other port. There you perform the same checks.
After that you closely examine the the LLDP and LACP information, as well as the logs of both switches, if everything is OK.
Since you seem to be using STP, you should verify STP operation as well.
Your configuration looks OK on first glance, I have not yet experienced problems with LACP between Cisco IOS and EXOS switches. Thus I'd say you need to dig deeper to find the root cause.