There is a potential bug when loading LRGB files. After you load each file (L, R, G, B), let StarTools finish processing the file (the spinning circle in the bottom right should not be visible anymore) before you load the next one. Otherwise the file won't load but will indicate it did. The result is usually nothing but the Lum when you continue processing.
This was discussed on CN here: https://www.cloudynights.com/topic/5699 ... +startools