You get an error when you try to find recommendations.
Symptoms
Too many failures while evaluating recommendations : Aborting recommendation cycle
Causes
If too many of the queries that are used by the recommendation engine are no longer valid or if too many recommendation candidates cannot be created, the recommendation engine stops because the recommendations are no longer reliable and effective. Queries are most likely invalid because the referenced objects such as columns, tables, or schemas no longer exist. Check the logs of the caching service to determine the exact cause.
Resolving the problem
Try to change the recommendation engine configuration settings to select a narrow window of valid input queries. For example, by selecting only previous 1 day of query workload. The problem might auto-resolve in the next few days, as newer valid queries are run and older invalid queries slide out of the window.