The problem is a setting in your widget blueprint details panel, possibly for each element in your hierarchy of widgets. Start from the first item (the blueprint name) and check that under “Behavior”, the “Visibility” dropdown is set to: "Not Hit-Testable (Self Only).
Go through each element in your widget hierarchy and if you do not want it to affect the mouse hovering feedback, set it to the above. As the canvas element covers the whole screen, set it to the above.
