Hi @Anonymous,
Since this morning, and probably due to the latest PowerApps core update a few hours ago (updated from 3.18113.22 to 3.18114.22), the DataSource property of the SharePointIntegration control in SharePoint customized forms keeps loosing its content.
Here is a video of what's happening:

As you can see, even though I refresh the datasource, the SharePointIntegration control keeps loosing the datasource.
This means that I'm stuck (and possibly many other people) and I can't modify my customized forms anymore... This is a real problem that would need a very quick fix...
Thanks for you quick reply,
Emmanuel.