Recommission of a decommissioned server is currently not supported. We need to add the server again into BSA once decommissioned.
Still give a try, raise a support ticket with BMC and check If we can update the UUID value for any server added (decommissioned) then your issue will be fixed. For this you need to identify the required schema details. BMC can guide which schema to look after (I have no idea which schema stores server details).
I may going little out of way with below one but you can think on this as well. If you are decommissioning a server and in future the same server is required to managed using BSA then use below logic to handle it.
Just update the IS_ONLINE property to false (instead of decommission the server). This property Indicates that the server is available for use or not within the system.
create server smart group with IS_ONLINE = FALSE and all the servers will be fall under this server group. You just need to take care that this server group is not selected as a target for any job.
does your issue resolved ?