Contain! does not prevent the targeted monster from being used as material for a summon.
Bug reproduction steps
Write the exact steps to reproduce the bug. Provide a replay code if you can. You can attach replay codes, or use a pastebin link or you can even use a spoiler tag using]
your replay code
Screenshot OR error code
After a monster is targeted is effects are negated, it cannot attack and if “Rescue-ACE Hydrant” is on the field, it cannot be used as material for a Fusion, Synchro, Xyz or Link summon.
What OS are you using