Same problem with version 2.8.2.2
Solution in my case:
Device Management > Groups > doble click in 1st camera > put Mainstream in First Record Stream. Copy to all cameras.
It worked perfect with my IP camera AVTECH EaZy mod AVN701ZAEZP/F36-ARG.
Funcionó perfecto con mi cámara IP AVTECH EaZy mod AVN701ZAEZP/F36-ARG.
Muchas gracias!!