When trying to convert a book from digi4school to pdf, it won't start converting and just show at the timeline "nicht berechenbar". This doesn't work with vector or rasterized.

It happens with every newer book. here is an example
https://a.digi4school.at/ebook/5845/

Steps to reproduce the behavior:

1. Open a book
2. click on convert
3. choose vector or rasterize (if rasterize, choose any quality level)
4. choose any page
5. click convert
6. it won't convert and won't break up the conversion
7. if you close the tab, an empty and broken pdf will be downloaded

A few Months ago, EVERY book converted and downloaded without any problems. 2 Months later, a few didn't work anymore. Now, the new added books won't convert entirely. If you repeat the steps above, you will get a broken pdf as a result. However these are the same steps I used a few months ago.

• OS: Windows 10

• Browser: Firefox

• Version: 91.0.2 (64-bit)

• OS: MacOs 11.6

• Browser: Firefox, Google Chrome

• Firefox Version: 91.0.2 (64-bit)

• Chrome Version: 93.0.4577.82 (Offizieller Build) (x86_64)

Not tested on a smartphone

I think its eather A: its not compatible with the browsers anymore and just needs an update
or B: the books have a small security shield. However I think its B because older books can still be converted. (a few at least)
I also hope, it fixes the scaling up bug too. Sometimes when you convert the hole book, it is scaled up so you only see a portion.

Describe the bug
Book never starts converting to pdf

Book URL
https://a.digi4school.at/ebook/3969/1/index.html?page=5

To Reproduce
Steps to reproduce the behavior:

1. Go to the ebook and open it
2. Click on the plugin and on the button "konvertieren"
3. Now the plugin window closes and nothing appens
4. See error:

Expected behavior
That the book starts to convert.

Browser(please complete the following information):

• OS: Windows 11
• Browser: Chrome
• Version 120.0.6099.72