basicConstraints with CA set to TRUE does not set CA to True

Vault
1

Hello There, I followed the instructions here.

  1. generating intermediate - used these params key_type=ec key_bits=256 add_basic_constraints=true

  2. defining role - used these params key_type=ec key_bits=256 key_usage=CertSign

Requested certificate (step #4), inspected the certificate and found out that CA is not set:

X509v3 extensions:
X509v3 Key Usage: critical
Certificate Sign
X509v3 Extended Key Usage:
Server Authentication, Client Authentication
X509v3 Subject Key Identifier:
E2:49:C9:DE:6E:C1:B1:F4:7A:08:5E:A3:33:DD:FD:64:8D:BC:5D:CE
X509v3 Authority Key Identifier:
keyid:C7:CF:67:D3:3C:10:5E:A2:4C:31:AD:D1:C4:FE:66:A2:E9:12:55:A7
X509v3 Subject Alternative Name:
DNS:test.example.com

Despite passing add_basic_constraints=true, CA is not set. What am I missing here? Any help is much appreciated.