Well, one reason that I can vouch for is that they either do NOT believe and never will, no matter what is put in front of them or what they discover or they do not WANT to believe. In other words, the SPR members are disbelievers as a whole and they prefer to push stuff away in a drawer and forget about it or just lose it.
I may be an oddity but I have seen ghosts all my life. It is nothing out of the ordinary to me and I currently share my home with Gladys, who died in the 1970s.
But I am very sceptical about poltergeists, summoning the dead via ouija boards, possession and other phenomenon such as levitating, head spinning and exorcisms.
If there were truth to magic all magic could summon the dead there is no black or white magic only magic with a good or evil intent. Necromancy could be used to good purpose...if it were possible of course