Despawning issues

Many of my things have been despawning even the things I name tagge . Its depressing as I've been all survival with achievements so you know I work twice as hard to get villagers into things. I had pandas and polar bears at my base over 1000 blocks of walking. Had them at my base for months and now they just despawn. I'm about to quit this game. Look into the hours I put into this only to lose all my work. Please fix this or there's no use playing