What is on screen should print, right?
Well, in a perfect world, yes, but this is just not how printing works. Printing isn't taking a screenshot of your application and translating it into printer-speak. Printing is converting your layout, objects and data into whatever format it thinks the printer needs based on the driver it's using.
Unfortunately as you've pointed out, it doesn't work on windows. The simple fact that it DOES work in OSX points to an OS problem with windows. This could be caused by whatever program is previewing the container content (IE acrobat), the printer driver, or yes, filemaker and windows itself.
Ways around the problem? I'm not sure what you've already tried, but I would consider making sure acrobat is up to date, or trying to test it with the full version of acrobat. Possibly trying out a different printer driver (IE PCL6 instead of PCL5, or even a PDF printer like PrimoPDF, CutePDF or NitroPDF).
Have you tried workarounds that don't use the container object? IE loading the PDF in a webviewer, or using a plugin like 360Works Supercontainer.
Filemaker 12 contained numerous "rewritten from the ground up" objects and functions. The entire front-end rendering is different as well. I feel for you that your solution stopped working post-conversion, but I don't think they could/can foresee all the issues that thousands of developers worldwide might have.
I understand the technical problems, but heck, printing is a fairly basic requirement, no? As for an OS problem, well, pdf's print fine enywhere else, just not in FileMaker containers.
Yes, we've tried different drivers, yes, I've tried web viewers. No I have not tried plugins, because this is like putting a band-aid on the problem and it cost the end user more money. for now, they use a Mac to print these, but it is incredibly frustrating for me, and the user who has paid very good money to FileMaker over the years. What can I say?
I suggest you to maybe contribute here :http://forums.filemaker.com/posts/bf077423db
And especially here : http://forums.filemaker.com/hives/1eea103f05/summary and add a new issue report...
Because you have good arguments !
Good luck, Fred