[obsolete] CNAME records already present, but ACM still marks the certificate as "Pending validation"

We have a certificate generating warnings about its validation status (three common names, three CNAME records required for validation).

The problem is those exact CNAME records were existing all this time (I have re-created the same records, using shorter TTL, but ACM still generates same warning).

How can I handle this without deleting the certificate (which will render related services unusable) and re-creating it anew?

Update of December 25. I had to replace the certificate instead of wasting more time on attempts to understand why ACM fails to conclude the validation (all the CNAME records were valid and in place for weeks, yet ACM refused to conclude the validation).

Honestly, I am very disappointed. ACM could provide the exact problem, so I could look into it, instead of giving vague pieces of advice (of the type "something is wrong").