Mobs despawning

Mojang: PLEASE FIX THE ISSUE OF NAMED MOBS DESPAWNING.  THIS HAS BEEN AN ISSUE FOR YEARS.  What is the point of playing a game so broken it doesn’t even follow its own rules? This needs to be fixed and should be an embarrassment to your company as people have been reporting this bug since the original release.  Please pay particular attention to why Polar Bears despawn, but it happens with any mob.  NAMED MOBS SHOULD NOT DESPAWN. Period. I am so tired of playing a broken game and even more tired of this particular issue not being resolved.