Note: this bug is related to a graphic glitch.
I believe that the alien power source scarcity problems have been fixed in this build. I found them much more frequently.
However, it seems that when reloading a ground combat save the alien power source is not reloaded.
It is still there, but it is not shown.
In the following screenshot the line of sight is correctly managed, as if there was the power source.
At the end of the mission, the power source was correctly retrieved from the crash site.