Issue when using 'PropertyDictionaryMultiple' as a backing type for a block in Commerce

Hi,

I have created a Block which I am using on a Commerce Product Node and am running into issues when adding a property and setting the backing type to be 'PropertyDictionaryMultiple'.  The editor is not rendering correctly, I am just seeing a text input, rather than a collection of check boxes.

When I move the same property down to the Product, it is rendered as expected.

Example below

[BackingType(typeof(PropertyDictionaryMultiple))]
[Display(Name = "Connectors2", Order = 7)]
[CultureSpecific]
public virtual PropertyList<string> Connectors2 { get; set; }

I am using Commerce '13.6.0'.

Looking at other posts it seems that this was reported and fixed in commerce 12.

Thanks