To improve solving of images taken with uncooled DSLR, I have introduced In the last version of ASTAP 0.9.321 a hot pixel filter. Hot pixels could be identified as stars . If they are below a specified size in arc-seconds they will be ignored by the filter. You can set the star minimum size in the ASTAP settings. This will have only a significant effect for uncooled sensors and if your using a small band filter. Most users will not require it.
The filter default setting it is set at 1.5 arcseconds but a typical setting will be 2 or 3 arc-seconds depending on your seeing and pixel size in arc-seconds. Try it on some short exposure images and see if the number of detected tetrahedrons increases. If it improves save the setting by leaving ASTAP by menu file, exit ( and save settings).
Note that If you have significant amount of hot pixels, they will show up in the ASTAP image inspector. Any single hot pixel will be ignored but if they show up as a pair they will be detected as a very small star. The filter has no effect in the CCD inspector.
An other available option to cope with hot pixels is calibration (dark subtraction) prior to solving.