In almost every MP games i played so far, my starbases doesnt upgrade if you chose any upgrade for it. You get charged for the upgrade, but nothing happens. Just shows you a little "1" in top corner of the selected upgrade, letting you know that you pick an upgrade. The progress bar well ... dont progress at all ^^ Hopefully you get fully refunded if you cancel the upgrade.
Since Vas starbases are supposed to be the anti starbase ship with the appropriate upgrade, it is pretty annoying not being able to upgrade it.
So I strongly suggest to create an anti structure ship for vas, like for advent and tec.