Hamster mystery - please can a hamster owner help

Hi everyone
I was hoping an experienced hamster owner could help with this query I have.
We recently lost our syrian hamster and there is no sign of her anywhere (food left untouched, no scratching noises, no nibble marks etc). She is usually very active and mobile so naturally we are concerned as its been 3 days and no sign anywhere despite having checked everywhere (small house, thoroughly searched all rooms multiple times).

She was being watched by our babysitter at the time who had put her in the hamster ball. She says the hamster was in there for less than 30 minutes before she realised she was missing and we started searching immediately. Our babysitter found the empty ball and says that it opened a bit down the middle but did not break into 2. She thought a few of the latches in the middle had come undone leaving a gap approx 0.8mm wide. I initially took this at face value but as still no signs of our hamsters anywhere its made me go back over everything.

I wanted to ask your thoughts on whether you think it would be possible for the hamster to escape from a ball that was not broken into two pieces? At rest the most it opens if some of the clamps are unlocked is less than 1cm. If i pull it apart from the outside it opens just about wide enough for her to escape but when I stop pulling it open it snaps closed again to leave only a small gap <1cm. I'm not sure if the hamster could push through the plastic from the inside as the plastic is also very hard and hurt my fingers when trying to do this.

I've never questioned anything babysitter said before and she seems nice/responsible but I just wanted to ask whether you think this would be possible as story seems strange to me.

Thanks so much