This issue occurs when the Task Sequence is advertised to a Collection but in smspxe.log still is a log message "No Boot Action for Device (x) found" where x is random number.
Resolution: It seems there is some caching in SCCM database that cause SCCM not be aware that this Task Sequence has been advertised to the collection.
Remove the manual entry of the computer account from SCCM Database, the collection and the Task Sequence.
After that recreate them again and it should start working.
To remove the computer account you can create Dynamic collection based on MAC address of the NIC.
The query is:
select SMS_R_SYSTEM.ResourceID,SMS_R_SYSTEM.ResourceType,SMS_R_SYSTEM.Name,SMS_R_SYSTEM.SMSUniqueIdentifier,SMS_R_SYSTEM.ResourceDomainORWorkgroup,SMS_R_SYSTEM.Client from SMS_R_System inner join SMS_G_System_NETWORK_ADAPTER on SMS_G_System_NETWORK_ADAPTER.ResourceID = SMS_R_System.ResourceId where SMS_G_System_NETWORK_ADAPTER.MACAddress = "xx:xx:xx:xx:xx:xx"
You should modify "xx:xx:xx:xx:xx:xx" with the MAC address of your computer.