When I switch from single to image sequence of an openEXR image sequence in the Compositor Panel, the backdrop disappears In a new blank scene, I open up the compositor dragging my multilayer OpenEXR sequence in. I can succesfully see a tiniy preview in the Image Node with the correct backdrop, but when I switch from single image to sequence, it disappears.

I attach 2 screenshots. Thank you all for the attention.





EDIT: I can't even use a File Output node, everything is correctly set up but there's no export in the folder (and a very fast render as nothing is calculated).
SOLVED: My OpenEXR multilayer has 10001,10002,10003... as suffix numbers. This means that the "offset" ot the Image Node must be set as 1000, to reach the frame 1,2,3 etc... Only importing the OpenEXR from the node folder, selecting all the images and clicking import, has forced Blender to automatically set the offset at 1000, resolving this issue. Of course this could be done manually.