I think it's a case of studio disinterest or ignorance.

Fox Movie Channel reruns JUST IMAGINE and CHANDU THE MAGICIAN ad nauseum; but they have never once run THE SPIDER, TRICK FOR TRICK, ALMOST MARRIED, BERKELEY SQUARE, SIX HOURS TO LIVE or LILIOM. Why? I'm guessing that nobody at Fox knows about these films. Or perhaps it's because they no longer have prints (Fox had a devastating fire in 1937 which destroyed the negatives for ALL of the studios pre-20th Century productions. Most of the aforementioned titles exist at MOMA, but who knows if Fox has copies).

Universal used to have the biggest and best horror package for TV syndication. But of all the Paramount titles the studio owned, only 3 made it into the package (THE ISLAND OF LOST SOULS, SUPERNATURAL and DR. CYCLOPS). Universal never had any interest in publicizing Paramount's three FU MANCHU movies, MURDER BY THE CLOCK, TERROR ABOARD, DOUBLE DOOR, THE WITCHING HOUR, THE SCOUNDREL or DEATH TAKES A HOLIDAY.

RETURN OF THE TERROR? Who knows? It was available for 16mm rental in the '70s. Have no idea why it has never been shown on television. Perhaps the print quality is substandard.

Columbia's TV horror package included NIGHT OF TERROR, THE BLACK ROOM, and the Karloff Mad Doctor series; but not THE NINTH GUEST. Why? Again... who knows?