Sigma Beta 11 is not yet finished. It will have some cool new features including a combine wizard, improved image management, and a blooming star repair tool.
However there is a Pre-Beta 11 available that includes these two bug fixes made over Beta 10:
1) Fixes 16-bit FITS file format save
2) Fixes reversed Hi/Low despeckle controls.
You can download the zipped EXE here. It is not a complete install. It is just a zipped executable that you can extract to any location on your hard drive, even copying over your Sigma Beta 10 exe:
Download Sigma Pre-Beta 11