I created a view in a SharePoint Online library where the Checked Out To field it Not Equal to "blank" meaning I didn't put anything into the field. This does not give me any results. How can I see all documents in a library that are currently checked out?
You need to have your view show where the Checked Out To field is Not Null. Unfortunately, although totally supported, this isn't an option in the UI. I wrote a post a while back where I did this same filter on the Checked Out To field:
The gist is that you'll need to edit the CAML query of the view directly using SharePoint Designer. Here's how that CAML might look for just that field:
<Where> <IsNotNull> <FieldRef Name="CheckoutUser"/> </IsNotNull> </Where>
Here's some documentation that may help as well: https://msdn.microsoft.com/en-us/library/office/ms465807.aspx