I have issues getting any result back from my sharepoint list. I have some jpg,ms word/excel and pdf files attached and sometimes i get results sometimes now. Any idea what is being actually crawled in the content sources for SP online? How do i know when was the last time the resource was crawled..i have re- indes so many times with no change If someone from MS team can give some clue here THanks in Advance
To get the last time the resource was crawled in SharePoint Online, you need to submit a ticket with Office 365 support.
For your issue, it might got instable search results for attachments in SharePoint Online. You can try to use the LinkOfficeChild managed property to show the attachment url.
Here is a similar post for your reference: Attachments Search O365