TenderBoard's Confidential Submissions function is activated to prevent supplier bids from being seen before closing to help assure suppliers that the bids are handled impartially. Thus, if your organisation has activated this functionality, you will not be able to view bids submitted until the purchase is closed.
Do note, however, that if you wish to check if the supplier has submitted their bid, you can follow the steps below.
First, on My Buylist, search for the purchase request using the search function. Next, click on "⋮" icon next and select audit trail.
On the audit trail page, you can view which supplies have submitted their bids.
You may also use the filter button (see on the left) in order to limit the selection just to bid submissions.