Wither not destroying blocks

I had attempted to make a farm from Wither destroying blocks when I saw it was not destroying blocks near it, so I tested a common way in which people would kill the Wither Boss underground, apparently It did not even try to break blocks to get to me even in survival mode. I know I was in The End when testing this. But the Wither is supposed to destroy all blocks except end portal frames bedrock, and end portal.