Sub-tasks vs Child issues ?

[Vakul]

In the Next-gen projects in the Jira cloud, we have sub-tasks and Child issues. Does anyone have any preference for using those? 

I see that we cannot have child issues blocking tasks, unlike subtasks. Both subtasks and child issues are not shown on board. 

Any insights are appreciated!

[S Fong]

Did you check the board setting > Column management (column constraint)?  It happens to me before on company managed projects but assume it's the same for yours.

[Linda Milne_Togetha Group_]

Sub-tasks and child tasks are the same thing. You can view the sub-tasks on the board using the group by drop down:

Not sure what you mean by "we cannot have child issues blocking tasks" - you would normally link tasks with a  blocks / is blocked by link, and you can do this with sub-tasks:

Note also that next gen is now called team managed, so use the latter to search the documentation.