When you manually edit and save the "Status" field, the flow fires correctly, this means there is nothing wrong with the configuration of the flow. The process builder did not trigger the flow.
A process builder field update does not trigger a "before flow" in the same transaction. A process builder field update will only cause the before trigger, after trigger and workflow rule to re-execute.
The order of execution is the reason.
- Manual updates the A2D record
- Before Flow runs (this is prior to the process builder execution)
- Before and After triggers execute
- Workflows Execute
- Process Builder Executes (causing #3 and #4 to re-execute)
- After Insert/Update Flow executes
- Record is saved to the database.
Hence you can see that your flow won't execute due to process builder field update in the same transaction. If you change your flow to After Insert/Update then you will see the desired result. Please give this a try.