Greetings,
First time poster long time lurker.
Just wanted to clarify that the OP probably meant the eaglenest map. I have just encountered the same problem as well.
I enclose herewith the ufoconsole.log and also the save game file.
When the the firestorm reaches the site, the map loads but crashes back to to the Geoscape leaving the firestorm idle.
In the save game file provided just click on the terror or harvest site and chose the nearest firestorm which is right on top of it.
You should be able to reproduce the same effect.
Del