Today I noticed some of my reports were empty like https://www.wikidata.org/w/index.php?title=Wikidata:WikiProject_sum_of_all_paintings/Image_suggestions/Creator,_institution_and_inventory_number_match&oldid=1416064318 and https://commons.wikimedia.org/w/index.php?title=User:Multichill/Same_image_without_Wikidata/Wikidata_creator,_institution_and_inventory_number_match&oldid=558322060 . After a bit of investigation I noticed a SPARQL query returning zero results.
The query https://w.wiki/3HvC used to run just fine (last successful run Thu May 6 15:00:25 UTC 2021). But stopped returning any results today. Just a minor change to the query (like removing the dots) will make it work again. What is going on here?