When an analysis is copied to a Dataset with different domain knowledge ('Ontology') or a Datasets domain knowledge is updated, Analyses will sometimes display a red warning flag. This signals that the Analysis contains Concepts that no longer exist in the dataset.
Analyses in this state should not be used as the figures they produce may be incorrect.
To fix the issue:
Open the Analysis
Go to the 'Edit' screen
Open any Insights with Red titles
Remove all Concept chips with Red warning icons and replace them with a similar Concept (using '+Add Pattern' is good for this)