Tune pki secret settings


I am trying to add allowed-response-headers=Last-Modified and passthrough-request-headers=If-Modified-Since to my pki secret by running:
vault secrets tune -allowed-response-headers=Last-Modified -passthrough-request-headers=If-Modified-Since pki-secret-test/ (tried only -allowed-response-headers=Last-Modified and only passthrough-request-headers=If-Modified-Since in separate commands also) and if I check vault read sys/mounts/pki-secret-test/tune I get:

Key                            Value
---                            -----
allowed_response_headers       [Last-Modified]
default_lease_ttl              768h
description                    n/a
force_no_cache                 false
max_lease_ttl                  768h
passthrough_request_headers    [If-Modified-Since]

So looks like command worked, but if I check in webui I see only one setting:

And I do not get Last-Modified response while sending request with curl. Any ideas appreciated, thank you.