Due Date (1) field can be completed in 3 ways:

This field is located on the second screen (5) of creation/edition form (available to get here on the "Set Issue Details" screen). It is present by default in all Jira Business (not Software) default projects.

This happens because all the fields on this screen (and other screens of TSP) are being taken from the Jira's fields, so if a particular field was disabled by Jira or Project admin, then you won't be able to see it here.

Moreover sometimes there are fields generated entirely by other add-ons and they may also be invisible or working in a faulty/glitch way. To resolve such issues feel free to get in touch with us.