My guess would be that vertices aren't welded along the edges. I can see it happening with the latch portion too. Since it sounds like you've checked that, I'd look and see if it isn't somehow becoming split in the export/import process, perhaps something to do with the seams because it is following those.

My other thing would be to try turning off the smooth polygons in Poser.

---

Available on Amazon for the Kindle E-Reader Monster of the North and The Shimmering Mage

Today I break my own personal record for the number of days for being alive.
Check out my store here or my free stuff here
I use Poser 13 and win 10