Short description:
After converting a world from the xbox one edition over to bedrock, you are unable to shear a adult sheep with wool. Unless they eat grass (and the values get updated), then you will be able to shear the sheep.

Steps to reproduce:
Convert a world with adult sheeps with wool from the console edition.
Don't let them eat grass.
Result:
You can't shear the sheep.
Note:
If you let them eat grass, although they had wool already, suddenly they can be sheared.

Attached images:
Test

Attached world receipt:

Attached video:
One of many little test
MCPE-25833.mp4