I am not seeing any problem light mapping models I have stacked UV's in.
I did notice one of my custom models had a few parts missing using DNSI textures and the entity_basic.fx shader.
Testing this more to see if I can spot a pattern.
RIP
Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz, 2400 Mhz, 4 Core(s), 4 Logical Processor(s), 8gb RAM, Nvidia gtx660, Windows 7 Pro 64bit, Screen resolution 1680 x 1050.
New:
Intel(R) Core(TM) i5-8400 CPU @ 2.81GHz, 12GB RAM, Nvidia gtx1050ti 4gb, Windows 10 Home 64bit, Screen resolution 1920 x 1080. System Passmark 3774