In a custom Forms 13 workflow, I'm trying to add a boolean setting. According to [the setting types docs](https://docs.umbraco.com/umbraco-forms/13.latest/developer/extending/adding-a-type/setting-types) I guess this should work:

[Umbraco.Forms.Core.Attributes.Setting("Message", View = "Checkbox")]
public bool Message { get; set; }

But the form becomes unsaveable (with no error message) if I add a workflow with such a setting. The checkbox does render, though. All `TextField`s work fine. Does anyone know for sure that this works? And, am I reading the docs correctly? Couldn't find an [issue](https://github.com/umbraco/Umbraco.Forms.Issues/issues) relating to this.