Error of Self-paced learning assignment - "the learning assignment couldn't be submitted"

Summary: Error of Self-paced learning assignment - "the learning assignment couldn't be submitted"

Content (please ensure you mask any confidential information): Hi to all,

If I go to the following Path:

• My Client Groups > Learning > Self-Paced Learning > Click in a course > "View Learning Assignments" button on the top > Add learners > Make an assignment

After inserting all information about the assignment in the 3 tabs, we click on "Submit" and then appears the following error:

What kind of error is? The functionality of "Self-paced learning" has been implemented recently to our client so I don't know if this feature can be relevant.