Posted originally by Ano Nima on Help forum post
When manually changing the job of a colonist to certain roles, the job title in the drop-down will cycle through a set of three or four jobs on its own until you close the colonist's information window. They will assume the next role in the cycle after the one displayed when you close the window. This doesn't happen with all job types, and there seems to be a common set among those that do. For example, if I go to set someone to be a doctor, they will cycle through doctor, technician, mathematician, astronomer and back to doctor again. For a botanist it goes botanist, driver, architect and back to botanist again. This cycling happens even with the simulation paused.
I tracked this down to difference in the order that job names were being displayed in the job combo box (alphabetically) and the order jobs were being returned from the job manager object. This created an endless loop of the code misinterpreting the selected job and trying to update itself. I fixed this by comparing the new job by name to the selected job in the combo box, rather than its index number. It now works as intended in 3.07 dev.