Dataflow refresh fails when chained but not when done independently

I have a stating dataflow A and a transformation dataflow B, where B refers to tables in A. When I refresh the flow A, it will also refresh B. Since yesterday, this chained refresh startred to fail during the refresh of B. In the error file, I could see something like below:

Error: Expression.Error: We cannot convert the value null to type Logical. . RootActivityId = <GUID>.Param1 = Expression.Error: We cannot convert the value null to type Logical. Request ID: <GUID>.

However, If I refresh the dataflow B independent of A, it finishes without any errros. Also, If I dispable the "Enable Load" options for the tables in B that are linked from A (this way the chained refresh between A and B will be disabled), and then refresh A anb B individually, both refreshes finish just fine.

So apparently "value null type Logical" has nothing to do with this error. Why does this happen and how can I enable chained refresh without causing such errors?