@Enrico Parisi 
No, NVARCHAR(8000) this doesn't work either.

I am using ensemble 2018 and database is SQL Server Management Studio 20

Things have slightly changed from our side. 

• initially used JSON to serialize data and pass it as a parameter to an INSERT statement. 
• Recently, we switched to storing XML data instead of JSON, and I am now trying to store this XML using the stored procedure

set tQuery="{ CALL dbo.SavePatientDetails (?) }"

Set tSC = ..Adapter.ExecuteProcedure(.tResultSnapshots, .tOutputParms, tQuery,,xmlContent)

Problem:

• Parameterized Query: Works fine when using VARCHAR(8000) as the parameter type in the stored procedure.
• Fails when using NVARCHAR(MAX) as the parameter type for passing XML data. The issue appears only when using the NVARCHAR(MAX) type, and I am unable to insert the XML content.

Your input is greatly appreciated. Thanks in advance for your help!

There are no errors returned. An empty string is being inserted into the database field, even though the trace shows the JSON correctly as {"CHI":"2894","Forename":"Janis"}.