My cloud os5 cannot share/print pdf files

I’m using the My cloud device I bought 4 years ago and have recently upgraded to OS5. So I have pdf files on the cloud and can view the pdf file through the my cloud OS5 app. But when trying to press the Share → Send a copy button (either to send it via e-mail or trying to send it to a printer app), there’s a brief pop-up that says “preparing to export…” and then nothing happens.

The same thing happens when I try to press the Open In button. There’s a brief “preparing to export…” pop-up and then nothing happens.

I’ve tried restarting my phone and tried the same thing on several phones and the same thing happens.

But for normal photos, the app opens and shares files normally.

Is there some settings I did wrong or does the app just not support pdf files in general?