Mark,
If you range of NDVI is from -0.28 to +0.38, it’s good. The NDVI range should be between -1 to +1. Stones, concrete, etc can have negative NDVI values and vegetation will have more than 0. Can you explain why you say “when the formula is used it does not make sense”?
For LWIR, +0.38 seems a very weird value, if after using the formula, Thermal_ir is 0.38, that would make sense as maybe the temperature of some object/pixel was 0.38 degree Celcius.
Can you send me a screenshot showing the NDVI and LWIR values?