Map or Ignore Indexer Property in Automapper 11 - automapper

Question

I'm having some issues mapping two classes using the AutoMapper in version 11. The destination class has an indexer-property, which causes the issue.
Since Automapper 11, the indexer property is no longer automatically ignored.
For testing purposes I used three classes:
public class Source {}
public class Target {
public float this[int key]
{
get
{
return 0;
}
set
{
}
}
}
public class MapperProfile: Profile
{
public MapperProfile()
{
CreateMap<Source, Target>();
}
}
During startup I'm calling mapper.ConfigurationProvider.AssertConfigurationIsValid() to validate the configuration. This fails with an unmapped Item property.
While it is possible to ignore all properties starting with Item using
this.AddGlobalIgnore("Item")
inside the Profile, I'd rather not use such a general way to ignore it, especially since the first parameter is labeled propertyNameStartingWith - this would suggest to me, that other properties such as ItemWithSuffix might be ignored as well.
Another strategy I tried to employ is to use an explicit ignore on a property. Using the expression notation fails, due to compiler errors:
CreateMap<Source, Target>()
.ForMember(dest => dest[], opt => opt.Ignore())
.ReverseMap();
Adding an arbitrary index to the expression fails with another error, so that does not seem to be a viable solution as well:
CreateMap<Source, Target>()
.ForMember(dest => dest[0], opt => opt.Ignore())
.ReverseMap();
In this case the error notes, that we may not map to child property.
When using the member name syntax, there are some different errors.
CreateMap<Source, Target>()
.ForMember("Item", opt => opt.Ignore())
.ReverseMap();
In this case it fails with the following message:
Incorrect number of arguments supplied for call to method 'Double get_Item(Int32)' (Parameter 'property')
Using [] or Item[] fails with a missing property notification.
The last strategy I employed was using the ForAllMembers call. This succeeds, however, I'm wondering if there is a better solution to handle this logic which allows using a specific mapping logic for a single member.
CreateMap<Source, Target>()
.ForAllMembers(x =>
{
if (x.DestinationMember.Name == "Item")
{
x.Ignore();
}
});