Status of lost episodes
From The Lost Media Wiki
I'm willing to bet the majority of these episodes are probably locked up in a vault somewhere but Disney is unwilling to release them because they don't want to ruin the reputation of the Winnie the Pooh franchise especially with the unsettling character designs and the fact that one of the specials addresses the topic of molestation. I can't imagine where else they would be put perhaps it is appropriate that more are found (and maybe more will be found) with the recent release of Christopher Robin.