path_regexp seems not working

Hi,
After tried w/o success to use path_regexp, I copy/paste your .sops.yaml example and give a try (with sops v.3.6.0):

$ sops a
Error encrypting the data key with one or more master keys: [failed to encrypt new data key with master key "arn:aws:kms:us-west-2:927034868273:key/fe86dd69-4132-404c-ab86-4269956b4500": Failed to call KMS encryption service: AccessDeniedException: 
	status code: 400, request id: 133014e9-8044-4944-9ce1-40760aecd564 failed to encrypt new data key with master key "arn:aws:kms:us-west-2:142069644989:key/846cfb17-373d-49b9-8baf-f36b04512e47": Failed to call KMS encryption service: AccessDeniedException: 
	status code: 400, request id: b881b03d-5e10-463e-837a-5dd38ba23ac5 failed to encrypt new data key with master key "arn:aws:kms:us-west-2:361527076523:key/5052f06a-5d3f-489e-b86c-57201e06f31e": Failed to call KMS encryption service: AccessDeniedException: 
	status code: 400, request id: 4aec7b97-bde8-4a93-b45b-1d37169b2895]

The regexp_path is \.dev\.yaml$ but any filename work. I tried everything, even empty and the regexp is validated.

Where am I wrong?

Start by reproducing the report with sops v3.6.0, the supplied .sops.yaml example, and the regexp_path value \.dev\.yaml$. Check whether the filename matching behavior can be separated from the reported AWS KMS AccessDeniedException; done means the cause is identified and a matching filename is handled as intended.