If I understand you clearly, Jide, your inverter is not bypassing power to your load or your house while on NEPA. If this is the problem you may have to explain what you experience where there is no power from the grid.
With your explanation, I suspect a faulty change over relay. This is probably a hardware fault and I advice you bring it to us at 15 Ajao Road, Ikeja for diagnosis.
You can send a Whatsapp message to us at 08157171707.
I look forward to your response.
Alternatively, you can use our online repair booking form to book us from any where in Nigeria. Our technician near you will contact you. We will arrange pickup and delivery of your inverter in good working condition. Use the form here to start