Custom Attributes no longer returned

GET /v1/company/employees?attributes[]=first_name&attributes[]=last_name&attributes[]=email&attributes[]=dynamic_7840856&attributes[]=position&attributes[]=dynamic_7663605 HTTP/1.1
Host: api.personio.de
Authorization: Bearer <token>

Expectation:
All attributes get returned.

Actual result:
Only standard attributes get returned.

Last time it was known to be working was 5th of July at 2:20PM. It is no longer working since at least 6th of July at 13:20PM. No changes were made to Personio or API implementation.

Kind regards,

Thomas