After liaising with one of our developers, this is the steps you should take to troubleshoot / resolve this.
First suggestion:
Clear Clients Internet Explorers Cache
Purge WinGate cache (GateKeeper) Caching --> What to purge --> Purge Now button
Then retest.
Second suggestion:
Stop the WinGate engine.
Navigate to: C:\Program Files\WinGate\Plugins\Kaspersky AntiVirus\Bases
Select everything, and delete.
Navigate to: C:\Program Files\WinGate\Plugins\Kaspersky AntiVirus\Downloads
Select everything, and delete.
Start the WinGate engine
Run the update. (Windows) Start menu --> Programs --> WinGate --> Plugins --> Kaspersky AntiVirus --> Kaspersky AntiVirus Updater
Then retest
Third suggestion:
Disable your personal AntiVirus scanner.
Download test file to your desktop
Do a manual scan on the file
Please let us know how you get on with this issue.