In V11, I have changed the sequence numbers for the task stages 'Done', 'Missed', and 'Cancelled' from 5, 6, and 7 respectively to 30, 40, and 50 respectively.  I did this because I use the project_gtd module which filters out any tasks that belong to a stage that has a sequence higher than 20.  This means that I don't see any tasks that are in a 'Done', 'Missed' or 'Cancelled' stage in the 'GTD' views that the project_gtd module creates.

This works fine, but from time to time the sequence numbers for those stages get reset to 5, 6 and 7 for no apparent reason.  This means that suddenly my GTD views are cluttered with hundreds of old tasks.

Can anyone suggest why the task stage sequence numbers would be changed without me editing them?  Is this something that Odoo does for it's own internal reasons?