Were Windows updates installed?
Sounds like a query or data issue. Do the affected reports have anything (e.g, a parameter) in common?
Did something change in stored procedure(s)? New data that might be inconsistent (e.g., null when null isn't expected or unexpected datatype or length)? Were reports re-deployed unbenownst?
Do you have trace files or extended events to show the queries that were executed? If not, I'd suggest reproducing to capture the queries.
In either case, execute the queries and look for the unexpected.