ValueError: Error when checking input: expected embedding_1_input to have shape (4,) but got array with shape (1,) numpy related
The model excepts the input to be a 1D array with 4 items. The current input single_x_test is a Python list with 1 item. The model implicitly converts the Python list to a 1D array but it still only has 1 item.

The model needs to be introspected to see what 4 items it expects as inputs. Typically items are separate channels of information.