dtuck90 and snogs,
My wife has exactly the same problem with BOTH her iPhone XR and iPad Pro 9.7.
On the iPad, if I Airdrop a PDF file to her device she sees the "Accept/Decline" dialog. When she selects "Accept" the PDF automatically opens in the Kindle app!
On her iPhone pressing "Accept" opens the PDF document in the Epson iPrint app (Kindle is not installed on the iPhone and Epson iPrint is not installed on the iPad).
Now if these apps are deleted from the respective device then pressing "Accept" brings up the normal Airdrop menu (see below).
I have reported the issue to Apple and it has now been escalated to Cupatino (I believe). I will post any outcome here when I get it.
I do have a temporary fix!
During testing with a senior Apple support person (thank you Trixy for your great help 😁😆😇) I was reinstalling the Kindle app; I noticed that the Apple Books app was adjacent to the Kindle app so I downloaded it as well.
With BOTH the Kindle AND Books apps installed pressing "Accept" produces the normal Airdrop menu (see below). This is NOT an ideal fix BUT it does work.
By the way, with both Kindle and Books apps installed, I deleted the Kindle app. Re-Airdroping the PDF file and pressing "Accept" causes the PDF document to be opened in the BOOKS APP! So you need BOTH apps installed.
Actually, you need TWO or more apps that can read PDF documents.
I hope this helps. I'll keep you informed, Apple Tech are due to get back to me early next week.
Regards,
Peter