My assignment rule is not getting applied to catalog task.

[Apex Predator]

I have a catalog item with a few fields. One of which is a select box called 'Problem Category'. I want to populate the assignment group of the task based on the problem category I select while creating the request.
This is my assignment rule.

This is my assign to field:

This is my catalog task with empty assignment group:

One think I noticed is, in the catalog task, when I save the form after I open it, it is assigning the group. 
But I need it to be assigned the first time I open it.
Any help or alternatives would be highly appreciated.
Thank you!

[Ashutosh Munot1]

Hi,

I think the first time it do not have a reference to variable and hence it is not working.

We usually set the assignment group from workflow or flow designer and not like this for catalog task.

Thanks,
Ashutosh

[Apex Predator]

Can you tell me or share a link how I can achieve this using workflow?

[Alok Das]

You can check advanced checkbox in Task activity in workflow and within the script you can use something like I provided in my other response.

[Apex Predator]

This is a solution but not the most ideal. I do not want to hard code the sys_ids nor do I want to invoke an extra database call. Thanks for the reply though. It certainly could have been a fall back strategy.