Evelynn becoming invisible while backing

Everyone knows Evelynn goes back into camouflage when she backs, but I just had a situation while she was backing in a bush that she went INVISIBLE before I got to her. The bush was warded, we were walking towards her, and as she went into her stealth mode she disappeared from sight even as I was right next to her.

The only step to repeat the bug I could say would be to have an Evelynn on the enemy team, and then wait for them to back in a bush.