Header Generator Error

[cfsdes]

When I try to use Generator with some headers, the payload don't work. For example:

# info to search robots.txt
id: test
type: fuzz
info:
  name: Robots
  risk: Low


payloads:
  - 'robots.txt'
  - 'teste'
    

requests:
  - generators:
      - Header("{{.payload}}", "Arbitraty")

When I use this template, the jaeles will send 2 requests using the header "Arbitraty" but with the same payload, which is the last payload that I set (in this case: teste)

However, if I change the Arbitraty word for Referer, it will work normally. This problem doesn't occurs only with some headers.