We're using 9.81 and have noticed a strange phenomenon where newly enrolled computers will change user assignment right after enrollment.
Our techs are using user-initiated enrollment to assign new computers to users. They input the AD username and get a checkmark. According to the logs, the JSS will change the assignment 1 minute later to an account that did not exist in the JSS previously. It seems to choose a random user from LDAP.
We did have wildcard turned on in LDAP settings, and just disabled this to test.