'flatAnnots' loses checkboxes on multiple pages

I have a PDF with multiple pages that has multiple types of existing form elements that I am programmatically filling out. I can do this successfully and save the output. I have added a file (before.png) as an attachment. I am also flattening each page of the PDF file with ( [page flatAnnots]; ) and then saving the output, so that the form elements can not be modified on a computer afterwards. I have also added this file (after.png) as an attachment. The problem I'm seeing is that the PDF file is missing the checkbox elements from anything after page 2 on the flattened file.

Is flattening the PDF file and losing form elements a bug?
Is there anything else I can do to flatten the file without losing form elements?
Is there anything else I can do to prevent form elements being modified without flattening the page?

May you provide your pdf file and screenshots, please?

I'm having trouble adding the attachments here. So, they can be viewed here:

before.png: www.dropbox.com/s/dowim664j0jspxz/before.png?dl=0
after.png: www.dropbox.com/s/dowim664j0jspxz/before.png?dl=0

you added twice the same image.

you should also provide your pdf to allow us doing some deeper test.

after.png: www.dropbox.com/s/7wubrdk5m4ogo98/after.png?dl=0

before.pdf: www.dropbox.com/s/ondoe5vd4wgjvbk/before.PDF?dl=0

after.pdf: www.dropbox.com/s/flnjpdfywmxbken/after.PDF?dl=0

Hi,

which SDK version are you using?
we checked the issue with the last stable version and it seems fixed.
You can download the updated SDK here: www.radaeepdf.com/download/file/83-radaeepdf-3-8-1