Edit:

A fix for the problem caused by DNN 4.4.0 has just been released on SnowCovered. The new version of Aggregator, 4.0.3 should only be installed on DNN 4.4.0 or higher. For all versions of DNN 4.x below 4.4.0, please install Aggregator 4.0.2. Thanks to everyone who provided testing.

Original:
The current version of Aggregator, v 4.0.2 has a small problem in DNN 4.4.0. When you save your Aggregator setup, an error is thrown (DotNetNuke.Common.Utilities.DataCache.ClearTabCache(Int32, Int32)).

I'm working on a fix for it as we speak. The work around is to just refresh the page after you save your settings. That should clear the error and everything should be fine. The error happens after the settings are saved so anything you put into the Aggregator should be there.

I should have a fix posted by the start of the week.