Error: Cannot use a CONTAINS or FREETEXT predicate on table or indexed view 'CMS_Attachment' because

So I have 2 Smart Search indices. Both of them are based on page types. Both have a search results page with filters (multiple drop-downs and a keyword). One is called Collections and one is called Projects.So when I do a keyword search on the Projects, I get this error message:Cannot use a CONTAINS or FREETEXT predicate on table or indexed view 'CMS_Attachment' because it is not full-text indexedIf I do a keyword search on Collections, it works fine. Using the drop-down filters on both works fine as well, it's just a keyword search on Projects that breaks.I have compared settings between the web part configurations and smart search index settings; both are virtually identical, except the drop-down filters are specific for each index. Both use the same DB. I have run the site locally and found where it breaks:Line 1479 - DataSet results = SearchHelper.Search(parameters);I have compared the parameters argument between the two searches and other than the index, page types, and path, there isn't anything apparently wrong with the Projects one.Please help, because I have run out ideas.