Different search results (BASIC vs ADVANCED)

I have elasticsearch up and running. with completed initialization and reindexing:

Elastic Search search model indexing status

Cabinet: 45
Document: 2463
Document file: 2463
Document file page: 36574
Document type: 1
Document version: 2463
Document version page: 36574
Group: 0
Index instance node: 6
Message: 0
Metadata type: 0
Role: 0
Signature capture: 0
Tag: 0
User: 0

Now I am targeting a document which contains a specific word “thermosolutal”. I know this document exists in my collection.
When I do a BASIC search:
“Document” search finds 13 of them, but my target document is not there.
“Document file” search finds 10, but my target is still missing.
“Document file page” search finds 10, but my target is still missing.
When I do a ADVANCED search:
“Document versions OCR” finds 32 documents and my target is there now.
“Document file pages” finds 29 documents and my target is still there.

So, my question is why do we have this difference between basic and advanced search features? Is basic search not reliable?
What is the best search practice to make sure I will find what I am looking for?