Hi Bobby,
This doesn't seem to be so much a StarTools issue, rather it is an issue with your dataset.
This behavior can happen if your dataset has values that are unnaturally smooth (e.g. large areas all with the same values, indicating no signal at all), or if your dataset has values that fall outside the allowable range specified in the image file header. What StarTools is doing in that case, is interpolating the faulty data values, hoping for the best. If most values are unusable for interpolation (because they are all corrupt, missing or containing 0 signal), the image you posted is the result; some stars poking through, but everything else interpolated because of bad values/signal.
If you are using DSS, for best results use setting similar to here;
https://www.startools.org/modules/intro ... uick-start
Can you confirm you are stacking RAW (e.g. CR2/ARW/NEF) files and not JPEGs?
Can you confirm you are not pre-processing the files CR2/ARW/NEF with any other software before passing to DSS?
Can you confirm you are not pre-processing the stack with any other software before passing to StarTools?
Can you confirm you are getting the same result if you
just stack the light frames without further calibration frames?
If you wish for us to have a look at your dataset, please feel free to upload it to GoogleDrive, Dropbox, etc. and share a link to it.
Do let us know if any of the above was helpful.