Never lose data in "Add More Tasks" inline form

We use "Add More Tasks" all the time and it generally works well. If all the fields are valid, it will save as expected. If instead the start data is accidentally before the project start date, it fails validation the inline form disappears and all the data you just entered is gone -- job roles or specific assigned users, description, etc. This is very frustrating when it happens and my users have complained loudly about it.

Example:

The date is invalid because of an accidental entry. Clicking off the inline form results in:


And the inline form is gone along with everything entered.