Hi Julien,
I'm facing a similar issue at a customer installation (ISE2.3 patch 5, Anyconnect 4.6), the issue appeared today at the morning at first login, as a workaround helpdesk disabled the aaa on the switchport and we are in the process of investigating.
For us everything worked with no issues in the lab and during the first days of the deployment.
At your case did it ever worked?
Thank you,Panos.
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