Audio missing on Libby and Hoopla

i have been listening to books on my iPhone 12 but a few days ago the book has no sound on Libby or on Hoopla. At first I thought it was my library card but no problem with that. I also checked my iPad. There is no problem with the books playing on the iPad. All other apps such as TikTok have sound.I can not think of anything else to do