You reported that Shaykh Ibn Baz holds that reciting al-Fatihah is a pillar, and that he considers it obligatory but does not consider it a pillar?

The questioner : Zayn, may Allah reward you. The opinion you reported from Shaykh 'Abd al-'Aziz is that he considers reciting al-Fatihah a pillar, as you said, whether in the past or recently?

The Shaykh : No, recently and in the past.

The questioner : Because the Shaykh has fatwas in Nur 'ala al-Dirb where it appears he considers it obligatory but does not consider it a pillar. Yes.

The Shaykh : No, he is merely lenient regarding the ma'mum (one praying behind the imam), for example if he forgets. According to the opinion that it is a pillar, the prayer is not valid.