Tahm Kench Skin Bug

Tahms Master chef skin has a bug with his ult, when a partner goes inside of him while the skin is on, it treats the target as devoured, i was doing this with my friend we practiced a combo with kalista and tahm but in the customs he didnt have the skin on, then we went into game with the skin on and the ult failed numerours times, we then went back to a customs with skin on, again nothing, we went in with skin off and the ult worked just fine it may just be that i was kalista but we were always oathsworn so that didnt cause any problems, please someone else confirm this for me and help settle this