Beug wooden barrier animals glitch

I built an enclosure to put Animals Cow, Sheep, Pig, Lama and a beug (crosses the wooden berry and it finds outside the enclosure)

The Glitch occurs after a certain time when have moved away and come back for example or times when there are a number or even when there are three or four Animals.

I play on version 1.11.2 in Vanilla

merci de regarder et de corriger le beug