If you are actually dragging on an attachment (eg, the blank space in an image) then Spine will select the image and you'll be manipulating that. You can toggled being able to select attachments with ctrl+i
(cmd+i
on Mac) so you can manipulate bones without selecting attachments.
I notice that if you drag on a region attachment in animate mode, it doesn't manipulate the bone. This isn't good behavior, we will improve it in the next beta version. You used to never be able to select region attachments in animate mode, but we enabled selecting them in the tree because it helps with adjusting draw order. Losing the bone selection when starting a drag on a region attachment is an unwanted side effect of that.