@rssportsbreaks
I can only make a suggestion as to what may be the issue. Your listings require a buyer to put up a payment source in order to make an offer to you. For which, when you accept their offer, they will be immediately be billed for the product. Their payment options will be limited, and there is no option to combine items or get an invoice for combined shipping. The process is routinely called "Auto-Pay".
Buyers, of course, were not particularly happy with this. Though it was supposed to cut down on non-payers, it served to discourage buyers that actually DO PAY as well, and I assume sales from offers and bidding declined.
Now eBay is rethinking this, and testing new procedures. They have not told anyone what these new procedures entail, but members have been showing and sharing screen shot pop-ups that indicating they are leaving accepted offers "live" i.e. for anyone to purchase until they are paid for. There was no mention of counter offers, but it is possible for you to accept offers from multiple buyers. We don't know if the tested procedures are a function of the BUYER or SELLER ID.
There is also some 'testing' going on with delaying the "auto-billing" for three days (instead of immediately) to allow time for combined invoicing.
Seller initiated offers have not yet been put into the "auto-pay" program, and perhaps it is just a matter of counter offers being counted as "seller initiated" and thus are simply waiting for payment? When eBay starts their tweaking and testing and provide no communication it is always difficult to determine if something is a glitch, or a new "enhancement".
You can always turn off your eBay awarded preferences (Defaulted to YES) and see if things go back to normal if you select NO:
https://www.ebay.com/bmgt/buyerrequirements
Buyer Payment Requirements
*Require buyers to provide a payment method before they place a bid.
*Require buyers to provide a payment method before they make an offer.
Click submit.
Do let us know if this helps.
