There is currently a bug with certificates LESS than master (master still works) and the player having a base skill of 300.
It is only a bug in this particular case. It works in all other cases.
Basically it does not give the proper exp and just evolves the trophy to the BASE (0%) of the certificate level not the 99% exp it should be doing.
I have fixed the bug, but it needs a full patch to go in. So in the meantime, if you have a skill of 300 and the certificate you have is NOT the master certificate, DO NOT DO THE COMBINE. Hold off until the next patch.
It is only a bug in this particular case. It works in all other cases.
Basically it does not give the proper exp and just evolves the trophy to the BASE (0%) of the certificate level not the 99% exp it should be doing.
I have fixed the bug, but it needs a full patch to go in. So in the meantime, if you have a skill of 300 and the certificate you have is NOT the master certificate, DO NOT DO THE COMBINE. Hold off until the next patch.

Ngreth Thergn