Confirmed for 1.14.
Can confirm this, I made a video showing the problem: https://youtu.be/-m0EGIwHzQU
I tried different designs to prevent falling down the platform, but nothing really worked well.
I think this only happens when you're in a snow biome where snow covers the whole surface and wolves are unable to teleport there because they cant find "unoccupied blocks".
I don't know whether the creator of this issue has experienced the problem in the same situation, so I didn't wanted to create a duplicate and instead I described my problem here.
I think they solved the problem in the 1.8.8 prerelease and didn't see there was a ticket opened here.
Can reproduce this too and waiting for Mojang to fix this asap as it is really annoying when changing a multiplayer server.
I searched already, but I didn't found anything 😞 Sorry!
But... Isn't it an other issue? It doesen't duplicates, it unlimits the item.
Can confirm for 1.14.1-pre2