Where is the photo?

You need to do one of three things:s

1 - if you know the file name of the photo search for it in the browser.

2 - add a unique keyword to the photo and search for the keyword in the browser.

3 - export the photo to the Desktop and navigate to the Desktop in the browser and select it there.

And tell Apple what missing features you'd like restored or new features added in Photos via Feedback - Photos - Apple

Not exactly sure if this would be helpful, but suggest you create an album (I named “Upload”) and point the photo to this album (it may be pointed to other albums - there is always just ONE photo), then if need to upload a photo, easy to find. Remove from album if down the road you no longer need it there (do not Delete unless you want it gone for good from any and all Albums).

On a Mac? Phone? iPad? If so what model and what version of the OS?