Trying to filter a list on its workflow status is pretty non-intuitive. You need the special status codes. Theese will work with all workflows in ShaePoint even Nintex workflows.
Status Code |
Status Description |
0 |
Not Started |
1 |
Failed on Start |
2 |
In Progress |
3 |
Error Occurred |
4 |
Cancelled (i.e. Stopped by User) |
5 |
Completed |
6 |
Failed on Start (retrying) |
7 |
Error Occurred (retrying) |
8 |
(unknown) |
9 |
(unknown) |
10 |
(unknown) |
11 |
(unknown) |
12 |
(unknown) |
13 |
(unknown) |
14 |
(unknown) |
15 |
Cancelled |
16 |
Approved |
17 |
Rejected |
Theese status codes can be used in editing list view query in both the user interface and the CAML in the list schema.xml
Another little special SharePoint speciality is that the workflow status field is referenced as the 8 first letters in the workflow instance name and the value type as WorkflowStatus
References: