You need to add the dependent fields in @api.depends of the computed function so that it's called when the corresponding fields are modified on the create() function.

Also a dirty trick is to set store=False on your computed field which will ensure that the compute function is always called, at least on each record fetching.

I see that compute works only for fields that is set on views(visible or not). Existing on view is the trigger compute function if not any @api.depends defined or store = False is set. I think this works like this because the value of computed field is needed to show to user. I realize that compute functions also works after create function works and record get it's ID unless computed field is called by another function before create function works. If you want to set value on create from code it is better to set default value with a lambda code. 

Do you set the value of the dependent fields in your create()? If the dependent fields' values not set the computed function will not be triggered.

in reply to @Khalid Hazam , I already have @api.depends, the computed field is computed correctly when i create a record using the UI, the problem is when I call the create() from code