Model Rendering Variant doesnt work with custom Sitecore SXA rendering

When you created a very simple Sitecore SXA rendering that supports Rendering Variants following Sitecore Documentation (https://doc.sitecore.com/developers/sxa/19/sitecore-experience-accelerator/en/build-a-rendering-that-includes-variants.html#UUID-db7bd5f9-8aa9-c04f-cc0d-478a4f913450_id__View) but when you use "Model" variant while creating a new rendering variant, regardless what you set in 'Property Path" field, even with just "Item.Paths.Path", it doesn't work and no html or any value is generated. 

Double check your cshtml and the line where @Html.RenderingVariants().RenderVariant is being called:

@using Sitecore.Extensions

@using Sitecore.XA.Foundation.MarkupDecorator.Extensions

@using Sitecore.XA.Foundation.SitecoreExtensions.Extensions

@using Sitecore.XA.Foundation.RenderingVariants.Extensions

@using Sitecore.XA.Foundation.RenderingVariants.Fields

@using Sitecore.XA.Foundation.Variants.Abstractions.Fields

@model PageTitle.Models.PageTitleModel

<div @Html.Sxa().Component("page-title", Model.Attributes)>

    <div class="component-content">

        <h1>@Model.CustomProperty</h1>

        @foreach (BaseVariantField variantField in Model.VariantFields)

        {

            @Html.RenderingVariants().RenderVariant(variantField, Model.Item, Model.RenderingWebEditingParams)

        }

    </div>

</div>

It needs to be "@Html.RenderingVariants().RenderVariant(variantField, Model.Item, Model.RenderingWebEditingParams, Model)" for the "Model" variant to work. After your change, the csthml should look like this:

@using Sitecore.Extensions

@using Sitecore.XA.Foundation.MarkupDecorator.Extensions

@using Sitecore.XA.Foundation.SitecoreExtensions.Extensions

@using Sitecore.XA.Foundation.RenderingVariants.Extensions

@using Sitecore.XA.Foundation.RenderingVariants.Fields

@using Sitecore.XA.Foundation.Variants.Abstractions.Fields

@model PageTitle.Models.PageTitleModel

<div @Html.Sxa().Component("page-title", Model.Attributes)>

    <div class="component-content">

        <h1>@Model.CustomProperty</h1>

        @foreach (BaseVariantField variantField in Model.VariantFields)

        {

            @Html.RenderingVariants().RenderVariant(variantField, Model.Item, Model.RenderingWebEditingParams, Model)

        }

    </div>

</div>

The reason is the "Model" argument is being used directly by the reflection method to find the values of the property that's defined, if that's not passed in, then no value can be retrieved.

A lot of articles online uses the same code just like on Sitecore Documentation site, hopefully this helps you if you are scratching your head trying to figure out why this doesn't work.