Bad end offset error when using PDF files over 1MB

Hello.

I have a WordPress site hosted on Pantheon that’s using the DearFlip plugin. The plugin works as expected if the PDF file size is less than 1MB. Files over 1MB show a “Bad end offset” error.

We’ve checked a number of different potential issues: PHP memory limits, server-side file compression, caching (as recommended in other support topics), etc. When visiting the URL of the file directly, it opens without issue. When using that same file in a flip book, we see the “Bad end offset” error.

The Pantheon site we’re testing on has no caching enabled on the server or edge (that I’m aware of), the PDF file does not appear to be compresses server-side, and we’re not using any third-party caching or performance plugins.

Any help and / or recommendations you could provide would be greatly appreciated.

Thanks.