The issue is that some IES files can't be loaded into Twilight Render. Some lamps models have different lumens, so I can download IES for each lumen and kelvin. Some of them result in invalid IES files, while the majority can be loaded.
For example, this is a link where you can find a mix of them:
https://www.lighting.philips.it/prof/la ... &layout=50
- 1270lm LED bulb with a valid IES file: https://www.lighting.philips.it/prof/la ... EU/product
- 620lm LED bulb with an invalid IES file: https://www.lighting.philips.it/prof/la ... EU/product
It's able to generate a report. This is why I think Twilight is a bit more strict, or may be this is a sort of bug? The strange fact is that TWR loads only the 1270lm IES file..**File does not include sufficient vertical data to properly calculate BUG and LCS uplight.
**File does not include upper hemisphere data(90-180) and has Cd > 0 at 90° vertical.