I recently had someone with no previous feedback score buy a book from me. I sent the invoice for payment and after a day received an email stating he/she does "not want to purchase the item due to personal problems" and request I cancel the sale.

I sent an email saying that Ebay rules do not permit me to cancel their purchase and that they had to do that themselves.

In the email I also asked what sort of personal problem could cause the purchase to not be completed. I have not received a reply yet.

I now notice the buyer has (1) feedback score. Given by a seller from US for the purchase of the same book the buyer wants to cancel from me.

Could experienced sellers advise me on what is a best course of action, please, I should take, if any...

Should I do nothing and leave it up to the buyer and/or Ebay to sort it out?