This happens a lot.
Whether it be the buyer getting busy and not being able to communicate efficiently or just plain forgetting. (especially around the holidays everyone is busy)
Or it might be the IM chat that every lil shit complains about bc they're salty 3rd party chat sales aren't allowed anymore
or might be trying to scam you lmao.
Research the person, if they're reputable and seem like they have a lot of customers, they probably do and just be patient.
If they're just some member that joined recently and isn't reputable at all, be cautious on making transactions with them.
Lot of people quickly join this forum seeing cheap deals and shit, post that they're looking for something and wanting to buy, then suddenly some random member pops into your IM / private message chat saying they can provide said item/service for a lower cost. You don't research the user, don't see that said person doesn't have anyone or anything to back him/her up. And ya get scammed and put in a scam report and get nothing out of it.