I'll try to get back to you with this issue as soon as possible.
Can you tell me what are you trying to do exactly?
As a workaround, I'd propose you to do:
- Create an entity that will store the binary date before making the resquest to the other page.
- Pass the entityId instead of the binary data.
- Use the GetRequest_Submit instead of the post.
- Read that on the request receiving page and delete the entityId you received.
This is just to prevent you from blocking while we investigate the cause for your problem.