Our Harry Houdini was an escape artist too, when he was a puppy.
He actually learnt how to open the slidey bolt thing on his (huge!!) crate....
If truth be told, I was actually very proud of his ingenuity...
He could do that, plus climb out of playpens (covered or not) - and if he couldn't climb, then he'd gradually chew his way out....
The only thing that truly worked for us was keeping him shut in our kitchen when we had to leave him - we even had to put a small bolt on 'this side' of the door, as he could jump high enough to push the handle down....
It all stopped once Harry had full-rein of our house....but that, of course, comes with time and age. Not to do with potty-training, but once he was passed the chewing (of wires, etc.) stage - once we 100% trusted him
It will all sort itself out, good luck!