The multiple devices API call combined with field 
filtering fails for us in the latest stable release, revision 12520 from
 
2023-02-08. The API call responds with an HTTP 200 but the data 
contained in the 
response is incomplete. It worked when we were on revision 12342 
from 2022-10-24. It still works if no filtering is requested.
After
 experimenting further and looking at the code we found that the 
multiple devices API call can successfully be combined with filtering 
only if device_id is one of the requested fields. We suspect this broke 
in revision 12452.
Works:
GET 
/api/v0/devices/?type=firewall
GET 
/api/v0/devices/?type=firewall&fields=status_type,device_id
GET
 /api/v0/devices/?type=firewall&fields=status_type
{"count":2,"status":"ok","devices":{"":{"status_type":"ok"}}}
Corwin