Javascript in PDF Form has no effect

At first, hi everybody

So i've registred because our company uses syncfusion a lot and sometimes there are strange effects showing up.
So my situation:
I have a PDF Template with some Fields.
In back I've set some javascript on the 'BeforeSave' event.
If i do save the document manually, it works fine.

But in code, we set the flag 'Flatten' of the PdfLoadedDocument to true and then save it with the save function.
But the javascript has no effect anymore. So i wonder, is the flatting done before the saving?
Is there a way to run the javascript before the flatting?
Another problem is: fields that are set to not visible, are rendered visible (i think its getting ignored at flatting)

Some ideas?
If needed, I can post more details or upload the pdf

Thanks!
Patrick

Thank you for using Syncfusion Products.

Please create the new Direct trac incident with simplified sample project which reproduces the issue.

it will help us to investigate further in this issue. 

Please let us know if you have any concern.

With Regards,

Praveen