How can I get a custom action to NOT show up on the toolbar?

I have a custom action to launch a custom report that's coded as follows:

    public PXAction<PMProject> projectRegDet;
    [PXUIField(DisplayName = "Project Register Detailed")]
    [PXButton(DisplayOnMainToolbar = false, CommitChanges = true, Category = "Reports")]
    protected virtual void ProjectRegDet()
    {
        PMProject proj = Base.Project.Current;

        if (proj.ContractCD != null)
        {
            Dictionary<string, string> parameters = new Dictionary<string, string>();
            parameters["ProjectID"] = proj.ContractCD;

            throw new PXReportRequiredException(parameters, "LFS99002", null);
        }
    }

It works fine, but I've added it to the 'Reports' section of the actions menu (in the ellipse actions) - and I can't get it to NOT show up on the toolbar. Everything I've tried makes no difference. The code you see is the last thing I tried - but before that I tried adding it to the Actions on the customization project, setting visible = false, adding a callback command in the ASPX and setting that visibility to false... nothing I do seems to make any difference. It just stays there on the toolbar.

Any ideas?

Thanks...

Apparently, this is an issue in my particular Acumatica instance - cause unknown - as I published in a client's instance and the button did NOT show up on the toolbar.