Power Bi report gets blank very often

Hi,

Recently, our client faced a strange issue in Power BI.

The power bi report, published in PBI service, becomes blank.

The type of connection is "import", the datasource is in Azure sql server. I checked , the data in Azure isn't empty.

The report is scheduled to get refreshed every hour from 6h to 20h ( so 15 times per day).

Seems to happen right before a scheduled refresh, but only periodically, not all the time and there is no refresh error.

But every time the results will come back.

I am trying to understand what can be the root cause of this issue, why the report data is getting BLANK and how can I prevent it to happen in future?