We have a Umbraco 9 site migrated from Umbraco 7 hosted on Azure - 1 app service, 1 SQL DB, storage... located in North Europe. Unregularly, the search pages which are using Lucene are returning no results! In the logs, we have only "Object reference..." log in such cases. The site has a different Search Index for each page with search functionality. We have a stage and a live environments and this is only happening to the live one. The site is pretty enormous from a content perspective and has a lot of customization but none is returning errors! Does somebody have the same issue? Any suggestions as to what can be causing this and how we can fix it?