There is an 80km stretch between Ourense and Santiago where ERTMS is deployed. However, RENFE has not certified the system for the Alvia in that section, as confirmed by ADIF desite the fact that Avant middle-distance trains on the sameline do use it. RENFE, asked by this paper, did not clarify why 13 months after hybrid Alvia started rolling there they still don't have that safety.

I found they gave an explanation later:

RENFE elaborates on ERTMS L1 problems with Alvia between Ourense and Santiago | ERTMS News

President of RENFE, Julio Gómez-Pomar, elaborated on the ERTMS problems of Alvia. He says that "on the hybrid trains S730 (formerly S130) we started to install the more advanced version of ERTMS. On the Madrid-Galicia line there are two sections that have ERTMS: Madrid-Olmedo (Valladolid) and Ourense-Santiago. When we started testing we saw that there were problems on both sections which we call transition failures: ERTMS ordered a brake intervention when the system was not supposed to do so. On the section Madrid-Olmedo the problem was eventually solved and the trains work fine with ERTMS now. But on the Ourense-Santiago section the problem persisted. We talked to the suppliers Bombardier to fix the problem. In the mean time, Adif authorized to disconnected ERTMS on that section and use ASFA to a maximum speed of 200 km/h. This is normal procedure.

Gah, so it was not strictly a problem of the hybrid train, but teething problems of [the software of?] the ETCS equipment programmed for the latest upgrade of the standard. (At any rate, it doesn't look like running on ETCS would have prevented the disaster on the non-ETCS section.)

_{*Lunatic*, n.
One whose delusions are out of fashion.}