Would a Seller’s Agent lie about another offer?

My partner and I put an offer on a house 5 days ago. The house has been on the market for 140 days and needed a good amount of work so we offered around 5% under asking. In our offer we asked for an answer in 24 hours. We heard back after 24 hours that they were expecting another offer and were going to wait on that offer. We were surprised, as was our realtor since the house has been sitting for so long and there were no other viewings before or after us.

Since then, our realtor has had a really hard time getting in contact with the Seller’s agent (not answering calls or texts for days) and all we have heard is that they are going back and forth on the other offer to see if they can make it work.

Are they just playing a game to see if we will go up in price?

EDIT: Thank you everyone for the input!! I had no idea we would get so many helpful responses.