Adding Task Type (sys_class_name) to a task form layout with lane field set to "state" makes tasks not movable across lanes


Description

Tasks can not be moved across lanes, with the error "STATE(resolved, new, etc states) is not a valid state for incident", after adding Task Type (sys_class_name) to a task's form layout with lane field set to "state".

Steps to Reproduce

1) Add Task Type (sys_class_name) field to any task type via Form Layout, i.e. incident, to the VTB view if existing, or else to the Default view.

2) Add a task of the same task type to a freeform board, as follows:
Name: something say "lanes by state for incident"
Owner: system administrator
Task table: incident
Lane field: state
Filter: "task type" is "incident".
Active: true

3) Open the VTB board.

4) Move tasks across lanes, i.e. from 'New' to 'In progress'. The error "In Progress is not a valid state for Incident" shows up.

Workaround

After carefully considering the severity and frequency of the issue, and the cost and risk of attempting a fix, it has been decided to not address this issue in any current or near future releases. We do not make this decision lightly, and we apologise for any inconvenience.

As a workaround, remove the Task Type (sys_class_name) field via Form Layout for VTB or Default views.


Related Problem: PRB1328398