A couple of remarks:
- The restrictions in the spec are a SHOULD instead of MUST
- There are no amdSec and dmdSec with status='CURRENT'
- The (ID's of) amdSec and dmdSec are referenced in the metadata structMap
The METS file in question: https://github.com/viaacode/documentation/blob/main/assets/sip_samples/2.1/film_standard_mkv/uuid-2746e598-75cd-47b5-9a3e-8df18e98bb95/METS.xml