Thanks Dave. I understand. For these particular PDFs my workaround is to open them in Preview and export as TIF, JPG or PNG all of which opened fine in AP. I don't need to edit the musical text or lyrics, just crop and move some elements around.
Congratulations on creating this app. I just started testing it and it shows great promise. I look forward to working through the Beta release. I usually use Pixelmator (or Ps) to open and crop a pdf of a piece of sheet music to prepare for publishing it in a document. It opens fine in PXM with transparent background but in Afp musical elements are misplaced (key signature and notes) and no transparency. Are there limits presently or other criteria a pdf must meet for opening correctlly? Steve