Each version of this integration matches a specific build of Unreal Engine 4. Here is what has changed in the 2019.1.9.7221.1609 release of the integration (in addition to upgrading to the new Unreal build).

Migration Notes 2019.1.9.7221.1609

Note: This integration does not support experimental Unreal Engine 4 features.

Unreal Engine 4.21/4.22/4.23/4.24/4.25 - Wwise 2019.1.9.7221.1609

• WG-47524 Fixed: Hang when using Event Callbacks from Blueprint during a garbage collection phase.
• WG-48046 Added support for Unreal 4.25.
• WG-48877 Added distribution of vc_160 libraries for all Windows Wwise sound engines and plug-in static libraries. (This is required for Unreal 4.25.) Removed specific distribution of vc_120 libraries in the Crankcase plug-in.