Does the Russian Air Force Even Know What Is Going On in Syria?
War Is Boring

You are forgeting one mayor factor so called Russia US cooperation where certain groups were not targeted because of US claiming they are good moderate beheaders.

We could write a similar article on why ISIS oil convoys were never attacked till Russians did it. Or why ISIS convois move trough iraq and syria under US watch .

Remember Russians are operating a small expeditionary force of airplanes for 1 year , while US led ‘coalition of moderate beheader suporters’ has run the show for last 5 year with no effect against ISIS