Office 365 Compliance search on File type

Hey folks!

I'm just wanna to search some attachments across my organization, and I encountered with some bizarre behavior. If I click on search and provide it some simple criterions, such as date, from, etc. I can see the results of such search. But I have a task to find some attachments. Previously in the stone edge on 2010-2013 platform there hasn't been such issues.

Now if I only choose just pdf (I tried with/and date or doc types and everything other) - this search just won't work- it didn't display any results at all.

Does this thing normal? Can anyone provide me working PowerShell  line just to search any needed file type?

PS. Used this link for actions

https://docs.microsoft.com/en-us/office365/securitycompliance/ediscovery-cases

https://support.office.com/en-gb/article/use-content-search-in-your-ediscovery-workflow-55f31488-288a-473a-9b9e-831a11e3711a