Fix implementation of custom due dates with rules attached to a project template

Scenario: I’ve created a project template to manage all deliverables associated with a single discrete campaign. The project template includes some custom columns for several different intermediate due dates for each asset on the way to its final publication date, some task templates that apply an “asset type” tag to the task and populate the description with some reference information, and some rules that automatically create and assign subtasks when the task is dragged to a particular section.

The subtasks vary by asset type, and the due dates of the subtasks are derived from the custom date fields. For example, the “design due” custom date on the parent task becomes the due date of the “design” subtask, the “copy due” custom date on the parent task becomes the due date of the “copy” subtask, and so on.

My problem is that every time I create a new project from this template, the subtask due dates in my rules all break and all have to be redone one by one. Example here - in the rule associated with the project template, this subtask is to be created “the day the Draft copy due:”

But after creating a project from that template, the same subtask creation rule now shows the due date as “The day is invalid, please recreate.”

Altogether this rule has around 15 subtasks that can potentially be created (depending on conditions met) where due dates are specified in the parent task’s custom date columns. Which means I have to fix this “day is invalid” error 15 times each time I create a new project.