Where are you saving the file?
When you save a file, you save to a specific location in your drive, so at the very least you should be able to navigate to that folder and find it. You should of course be able to find it using search.
If a search fails to find a file that you know it exists, there could be a problem with Spotlight.
The default remedy is to reset the Spotlight index:
Go to System Settings->Siri & Spotlight; click Spotligh Privacy; drag the whole drive to the box.
Then close this window, close System Settings; open System Settings again, select the drive in the Privcy Box and press "-".
This forces Spotlight to reindex the whole drive again.

For some people (me included) there was at times a problem in that Spotlight worked fine if searching "This Mac", but could not find anything if you selected a specific folder - even when one is staring at a file right there.
This too can be fixed. Let us know if the procedure above helped or not, and if the search problems are overall or only when searching within a folder.