Texture Files imported from 16 bit sources cannot be exported

Textures files that are imported into the engine from 16 bit PNG files cannot be exported from the engine.

Also Reproduced in Main Promotable-CL-2473270

1. Open QAGame Editor
2. Import the attached 16_Test and 8_Test PNG Files
3. Save All
4. Select Both 16_Test and 8_Test, Righ Click >> Asset Actions >> Bulk Export
5. Export files to Desktop

RESULTS: Only 8_Test successfully exports

EXPECTED: 16_Test and 8_Test both successfully export