Hello,
From what I can tell what is happening is that you can only see 3 items in 1 Sharepoint Online (SPO) library or folder but you know there is more. Am I correct?
If that is the case you could try creating a New View:
And then make sure the view shows all items or the ones you want to show in the editing options:
I hope this helps unless the issue is something different, but I couldn't tell.
~DF