Well it is a WMR issue related to the Cliff House. What is happening is that you have likely skipped, or not completed, the Cliff House routine of looking left, looking right, and looking down. This centres the headgear in real space. Then launch SteamVR for WMR and then iL-2. You should be able to move your head around the cockpit. Reboot implicitly works as well only because you probably ended up completing the alignment process. Just as effective although rebooting requires more cuss words.