VAInterface is not yet compatible with Prepar3D V4.
We were working hard to implement that support and have faced many issues during the past weeks, but we think we have finally reached out a candidate beta release:
This zip file contains the new VAInterface 126.96.36.19939 and its companion Control Panel.
Just download it to the existing VAInterface folder and unzip it there.
Then run it by right clicking the file name and selecting Run as administrator:
You may need to set firewall and/or anti-virus rules for it as well.
If you find any issues, please submit a Technical support ticket and attach the VAInterface logs.
VA Support Team