Cache completed entities during incomplete refresh

One of the strengths of PowerQuery is its ability to work across multiple different types of data sources, & transform and combine the data it receives.

When dealing with such diverse data sources, we also deal with diverse performance and system availability characteristics. In a moderately complex report connecting to multiple different datasources, *a single entity's failure to refresh negates all other successful operations.*

Suggestion:
PowerBI should add completed entities to the internal cache, and provide a ui option to refresh just the failed entities in a second (or third, etc.) attempt.