Maybe it's a depth buffer issue because of it's low accuracy...which GPU does your device use and have you tried it in another one with a different GPU? Nvidia Tegra and Adreno are known for low accuracy...if that applies here, there's a helper class in util, the NVDepthConfigChooser which you can use as your config chooser at init time to improve depth buffer accuracy on both chips.
If it's not that, maybe the objects are transparent and it's a sorting issue of some kind? Sometimes, exporters add transparency informations to objects that actually have none. In that case, try a setTransparency(-1) on all objects after loading.