Supported drive Format Fat32 / NTFS?
Max drive size?
Not that we're aware. We've used an 8 GB USB flash drive.
Max number of slides?
No limit other than total space fitting on the USB flash drive.
Do all the slide need to be in the root or can separate slide shows be place in folders?
They can be categorized by folders.
Picture format bmp jpeg?
The following formats are supported: .bmp, .gif, .jpg, and .png
Max picture resolution?
FYI, if you don't already have it, here's a link to the product manual:
About the issue you reported, I've asked our Engineering group if we're aware of any limitations regarding the file names. That was my first thought as to what might be causing this issue. Please keep me updated with any further details, i.e. troubleshooting on your end, and I'll let you know what our Engineering group has to say.