Incorrect (Empty) HTML5 time input fields after IEF re-edit

Setup:
- Enable module 'Entity Construction Kit' (ECK)
- Enable module 'Inline Entity Form' (IEF)
- Create an ECK type with some fields and a Office hours field.
- Create a Node type with Entity Reference to the ECK type
- In Manage form display of the Node type: Choose IEF - Complex.
- Create a node and create with IEF the Office hours.
- Before saving the node, edit the created Office hours (IEF).
- Result: The HTML5 time input fields are now empty.

This only happens with HTML5 time input and when the IEF has been saved, but not the node.