In Windows 10, Microsoft since Windows 10 (1809) has introduced a new tool called "Snip & Sketch" Windows App (package name "Microsoft.ScreenSketch" intended to replace the trusty Snipping Tool (SnippingTool.exe).
The Snip&Sketch can capture the screen (rectangle, free form, etc) like the SnippingTool, however the images it produces for some inexplicable reason cannot be pasted into a document with LibreOffice Writer. The Ctrl-V in LibreOffice does not work.
There are two ways to invoke it:
1) You can invoke it by launching (use the search) "Snip & Sketch" which is a Windows App. You can recognise it by its appearance once launched.
2) Or you can press the Windows short cut key: Windows Logo Key + Shift + S, this launches the Snipping bar
If one uses Method 1) the captured image is inaccessible to LibreOffice Writer. I have experimented with AbiWord, KeepNote, and CherryTree, programs that can embed images into their document and they are all working fine.
Only LibreOffice Writer (ver 6.1.63, 6.3.5, and 6.4.1.2 all running Windows 10 1903) is failing the test. With these versions of LibreOffice running in brand new laptops, old laptops and desktop, I cannot reproduce the claimed effect stated in LibreOffice site.
Method 2) is the most reliable method as it works with Microsoft and LibreOffice Writer. When that short cut key is pressed, a small bar called Snipping Bar pops up on the top roll of the screen. With that the user can choose how to capture like the trusty SnippingTool.
While the snipping bar does not have any menu item to indicate you can save the image, crop, or annotate etc, once an screen portion is captured, Windows will display a transient message window showing the captured part and informing the user that it has been sent to the clipboard.
This transient window will then appear in the notification collection. If you are quick enough, you can click on that transient window to launch the "Snip & Sketch" App with the captured image embedded in it allowing you to do the "Sketch" or File save part.
If you want to use the "Snip & Sketch" to annotate, crop, etc on the capture image and then paste that into LibreOffice Writer, here are the steps:
1) Once you have completed the process with "Snip & Sketch", press the "Copy" icon just to be sure the right image is transferred to the clipboard
2) Open MS Paint (paint), Paste the image to it.
3) Use the Select tool (mostly I use Rectangular Selection) to select the part you want to paste into your document
4) Then press the Copy (or Ctrl-C) to deposit it onto the clipboard.
5) Switch to your tool that you want to paste the image and press Paste (or Ctrl-V).
There is no need to involve saving to file. It is already clumsy enough.
It seems the fault is in LibreOffice Writer.