Unity 2019.1.5f1 complains NativeContainer not assigned (.4 did not)

Just updated from .4 to .5 and receive this error:

InvalidOperationException: The NativeContainer JointCreationJob.entitiesWithJointCreationQueued has not been assigned or constructed. All containers must be valid when scheduling a job.​

I allocate it in my Job at the top of

Execute()

with

NativeList<Entity>(count, Allocator.Temp)

and

Dispose()

of at the bottom. It's assigned to a private member of the Job struct just to save passing it to every call of a sub-method. Is this new .5 behaviour correctly reported as wrong, is this a bug or have I missed something (maybe an annotation to indicate use)?

Thanks.

 

Maybe it is the Dispose() --- Temp allocated containers are automatically disposed and do not need a manual call

 

Show code

Also if you're allocating within a job (temp) don't call dispose on it