Each version of this integration matches a specific build of Unreal Engine 4. Here is what has changed between the 2018.1.3.6784.1177 and the 2018.1.4.6807.1189 release of the integration (in addition to upgrading to the new Unreal build).

Unreal Engine 4.19/4.20/4.21 - Wwise 2018.1.4.6807.1189

• WG-39671: Exposed ExecuteActionOnEvent to Blueprint.
• WG-40333: Ensured all PostEvent calls go through the Callback Manager.
• WG-40344: Exposed GetSpeakerAngles and SetSpeakerAngles in Blueprint.
• WG-40365: Changed SoundBank generation message to make it clearer that the SoundBank can be generated but still have errors.
• WG-40380: Prevented crash when calling PostAkEventAndWaitForEnd with an invalid AkEvent.