When using the node Add Loading Splash Screen the delta rotation does not appear to update/rotate the texture that is applied as the tool tip appears to suggest ("(in)" Incremental rotation, that is added each 2nd frame to the quad transform. The quad is rotated around the center of the quad")
Note: In this test you can press the '1' key to have show splash screen called on tick
Result: The Texture for the splash screen does not rotate
Expected: The Texture would be updating every other frame and it would appear to rotate
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-73078 in the post.