I have the same behavior. The autoupdate seems to work but when I open Ctrl + Alt + C it shows the old version number, even after manually restarting VA.
My VA shows this when autoupdating:
20.57.36 - Plugin 'VAICOM PRO 2.5' initialized.
20.57.36 - Ready for commands.
20.57.35 - Installing...
20.57.35 - Package download complete.
20.56.35 - Downloading package.....
20.56.35 - Executing automatic update.
20.55.01 - New update available!
20.55.01 - Initializing..
20.55.01 - Press LCtrl+LAlt+C for config.
20.55.01 - VAICOM PRO for DCS World. License: PRO
20.55.00 - Plugin support enabled.
This goes back to before AIRIO came out. I have gotten into a habit of downloading the latest .DLLs and replace the old ones after every update.