I connected my iPhone with the DDJ-WeGO4/DDJ-WeGO3 but cannot control WeDJ for iPhone.

Turn off the power of the DDJ-WeGO4/DDJ-WeGO3 and the iPhone without disconnecting them. Follow the instructions below.
1) Turn on the power of the iPhone.
2) Turn on the power of the DDJ-WeGO4/DDJ-WeGO3.
3) Launch WeDJ for iPhone.
If WeDJ for iPhone does not recognize the controller even after the above procedures, please contact our support site.
https://www.pioneerdj.com/en/landing/app-inquiries/