MongoDB.Driver.MongoCommandException: "Command aggregate failed: Variable $$SEARCH_META not supported yet."

Hi,

I'm trying to migrate an app from MongoDB Atlas to Azure MongoDB vCore.

We're using C# code to run an aggregation pipeline but this is failing with the error message

MongoDB.Driver.MongoCommandException: "Command aggregate failed: Variable $$SEARCH_META not supported yet."

This is the code snippet:

IEnumerable<ProductBase> result = await GetCollection<ProductBase>().Aggregate() 
                  .Project<ProductBase>(Builders<ProductBase>.Projection
                          .SearchMeta(x => x.MetaResult)

I wonder why this is failing because in the docs we see that searchMeta is supported on MongoDB in Azure.

https://video2.skills-academy.com/en-us/azure/cosmos-db/mongodb/vcore/compatibility

Can anyone help?