This issue was causing us some concern and we could not find any reference to it on any forum or partnersource so now we have an answer, I thought I would put it on the blog so the rest of the community was aware and maybe save some people some serious head scratching.
The issue is this, when exporting to excel from Dynamics GP 2013 smartlists it was crashing out when reaching row 32766.
All the DEX developers out there are now going “oh , Oh , 32766, that’s the maximum integer value in Dex” and you would be right. Here in lies the problem, the smartlist code in Dynamics GP2013 has been rewritten to speed it up. It used to do it line by line but it is now casting to an integer.
The folks at Microsoft Dynamics GP Technical Support have been great helping us with this (thanks folks you're all stars) and it has now been written up as a change request and sent to development.
I’ll update the blog when we get a date, however in the mean time you just need to be aware this limitation exists.