Thank you for this report. Our developers are aware of this issue and they are currently working on it.

As soon as they prepare a fix, it will be released. Please be patient, it may take some time. Thank you for understanding.

The waiting period has ended. The choice to build combine HQ appears. I select the location from the list of available spots, and click to build the HQ. Message pops up briefly stating that Combine HQ is being built, but nothing happens. I restart computer, and reload game. The only thing that happens is that I can repeat the process with still no results.