If you don't have EDP enabled on the LAG ports, enable it and run the command show edp ports all. You should be able to see what ports on the switch are live, and what remote ports they are connected to. That's a good place to start
# show edp ports all
Port Neighbor Neighbor-ID Remote Age Num
Port Vlans
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20 X460-24p 00:00:00:04:96:98:7d:96 1:20 58 1
22 X460-24p 00:00:00:04:96:98:7d:96 1:23 45 1
=============================================================================The Defaulted state of a LAG port occurs when it does not receive an LACPDU from the partner within the specified hello time, you can check the LACP counters on both switches and see if LACPDUs that are being sent from one switch are arriving on the other. Until the LAG is fully formed, you will most definitely see dropped data traffic.