If you are at a considerable distance for the allay follow you this one will not follow you if it is tied to a leash, but it will follow you if you disconnect and re-enter, the coordinates where the allay was tied when I disconnected was at 304 64 92 and where I disconnected was at 245 63 45 this I know because every time I leave the world I make a backup.

 Steps to reproduce:

1. Create a world with the seed 933362424
2. Put a fence at the coordinates 304 64 45
3. Summon an allay, give it an item, put a rope and tie it to the fence
4. Teleport at the coordinates 245 63 92
5. Leave the world and re-enter
6. Go where the allay is

The observed result:
The allay follows you and the leash breaks.

The expected result:
The allay does not follow you and the leash does not break.

here is the link