Missing data after refreshing dataflow.

Hello,

I have issues with my dataflows. In my dataflows, I use excel files from Sharepoint and others dataflows as sources.
When I try to refresh dataflow either I get null data nor miss-match data. But queries work well in query editor in both Desktop & Service.

I do multiple combining steps in the same query. And when I put the different applied steps in different queries, it seems to work. So I think the issue come from the Merge/Append steps but i don't know why or if this is really the cause of the problem, it remains a hypothesis.

I specify that it worked perfectly two months ago with the same queries. I had no problem updating dataflows. And the queries work in the query editor. The problem occurs when I launch the dataflow by clicking on the refresh button.

Has anyone else had this kind of problem ? May be this is due to updates to the Power BI Service (dataflow) on the Microsoft side.

Thank you !!