It will let me save a soundfont larger than 2gb and it works fine with my synth, but when I open it up again it crashes.
I've been able to reproduce this on 1.7, 1.8, and 1.9. In both windows and ubuntu. All of them using the 64bit version.
Looks like Polyphone can't open sf2 files that are 2gb or larger. It can SAVE them though...
Not a big issue as I'm probably the only one effected by this, and my synth allows me to use multiple sf2 files so I can workaround this without much trouble.
Please let me know if you wish me to provide a file that's over 2gb
It may appear to save the soundfont and playback but it is corrupted as the 2Gb limit has not been addressed in the software code (it isn't an sf2 format limitation). I recommend opening your work with another editor that can read and write such soundfonts so you can at least see all your settings. Then recreate your soundfont and make regular backups (copy it to other folders/drives for safety).
This problem was reported over a year ago, it's a shame it hasn't been fixed yet. It's a simple oversight and should be easily corrected. Around the same time I reported the error to the author of the Viena soundfont editor and that can now read and write 2Gb+ soundfonts without errors. Though my soundfont is now smaller in size I still use Polyphone, but if you don't want to optimise it and make it smaller you could try Viena (http://www.synthfont.com).
I've kept backups of my work, I lost progress over this but not much.
Viena hasn't fixed this properly yet either, it seems to drop random samples with files over 2gb. I don't like Viena's UI at all so I haven't bothered reporting that bug with them.
This issue may seem simple to resolve, but depending on there code it might actually be pretty tricky to implement, they may have to rewrite a number of file IO functions to be fully 64bit address aware. I'm not overly concerned but it has been a minor annoyance for my midi project.