I had to read 3 PDF files in a recent email. Open the first file with no problems. When opening the remaining files, problem occurs. Could see 'Adobe Acrobat Reader' logo screen going through the loading process. Then logo screen disappear thinking the process is completed and file will open. Turns out the screen would remain black for a few minutes until I hit the HOME button to exit the app. After waiting a few minutes and restart the phone, try opening the files again (including the original file). Again, I would see the logo screen and then black screen. Thought it might be the email server, so went to a govt website to read a PDF file (previously able to open and read) I needed. Same issue happens.
Could you please share the device and OS version you are using? Is the problem also happening when you download the PDF and try to open it using Adobe Acrobat app? If so, would it be possible for you to share the PDF file with us at firstname.lastname@example.org?
Adobe Acrobat Team