Using constants for label causes 'X' (errors) or (warning) but works fine

[rechtapia-16420]

Im using constants in our manifes.lkml for labels

constant: tie {
  value: "Tienda"
  export: override_optional
}

It generates this error but if I validate it with “validate LookML” it is ok. It sometimes disappears. Nothings seems to be broken and works fine.

This reappears and reappears everythime I refresh the website. Its not appealing and bothers my work. What can I do?