Calibre 8.10 Book Viewer not displaying text

Hi all,

The Calibre 8.10 Book Viewer is not displaying text properly. This is an issue with every book in the Library (all epubs). Instead I just see a wall of question marks each within a square. I have attached a screenshot. These books will display correctly in the Books.app using "Open with." I am on MacOS Sequoia 15.7 using a M2 Mac Mini. The Calibre library is stored on an external hard drive. Other files on that hard drive open properly in their respective applications. I have restarted the computer and reinstalled Calibre to no avail. Any ideas what the issue might be?

Thanks

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