Businesses have the option to invite Operators to bid on certain Ops. They may be selecting individual Operators or they could be inviting their entire labor pool. This is why even if you have been invited, the invite does not guarantee an accepted bid. It simply means that the business would like for you to bid on their Op. The business may have 10 open spots, but they have invited 100 Operators to bid, so then the business must select the 10 bids that they want to accept out of 100 possible bids.