did you solve this problem?
I´ve got a similar behaviour ( AR X and AR XI) on a 2008R2 with XenApp 6.0.
If you click on an PDF in a Lotus Notes document, the pdf is opened in AR. But if you want to print it from AR, there are no printers to select except XPS Printer. In Lotrus Notes printers can be selected at this moment. Office workes fine too.
After saving the document to disk, it can be opened by AR and priters can be selected.
This reported behaviour is not constant. It seems to be more often in slower attached environments.