In 2019 I am experiencing the same issue with the same use case. Every time I had a medical expense in 2019, I snapped a picture of the receipt and added that picture to a new note in a 2019 taxes notebook. I am using iOS.
When I go to view the notes in iOS, anything before September no longer shows the picture (just the small empty square).
When I attempt to view the note on Mac, NONE of the the pictures show up.
I also have Scannable documents that have the click to download on iOS, but never downloads.
On Mac (again) nothing shows up.
For a services that is intended to retain information, it is failing at the services fundamental purpose. This is not acceptable and I must be insane to continue to pay for this service.