This started with GRAV, continued with ARK, and is once again happening with FortNite. Unreal Engine 4 causes issues where executable files get locked out of Windows control because they are not closing properly. There is no running process but if you try to update file (as programs like Steam and Epic Launcher try to do) or delete it manually, you will find you don’t have access to do so. Using Process Explorer I am able to discover that executable file’s “Handle” requires closing before access can be given to do anything with it, such as deletion, updating, or execution.
Considering this problem has happened with all 3 of games I’ve listed above, it seems to be a bug inherent to engine itself. I suggest you look closely into how your games are closing, it seems they do not do it well. I’m running on a Windows 7 64-bit system that’s never witnessed this problem with any other engine or program. I’ve never had to specifically close file handles through process explorer before.
Please let me know how I can help with this issue. Unfortunately, it is not reproducible effectively as it only happens about 5% of time when I go to play (or have updates for) one of games I’ve mentioned above.