Newsflash: Is this practice normal or unethical?

I’m the buyer. My agent called the seller’s agent to find out if they have any offers in hand and are accepting escalation. She says they have an offer and yes escalation is fine. So we put in an offer with escalation (using fake number – asking price $700k and max $760k). In early evening, she reaches out to my agent to say we are in the lead at $755k but the sellers want to make a decision the next day. The next day she reaches out to my agent to say we are now tied at $755k and only wants best and final offer and no escalation. How are we tied if my max was $760k?Seller’s agent said she will provide us the other offer, but have failed to do so. Isn’t she supposed to show us the other offer? Is this practice normal? Is this just the seller trying to milk more out of me? Seems pretty unethical to dismiss the max on the escalation.