FIM Microsoft Powershell MA - Refresh schema

I have a couple of Microsoft Powershell MAs in a customers FIM solution using a SQL source. I needed to add an extra data attribute to the SQL data which I did in the SQL script and then added the attribute to the schema script area of the MA

$SchemaType | Add-FIMSchemaAttribute -Name 'NewAttribute1' -DataType 'Int' -SupportedOperation -ImportOnly

After saving the change I did a Refresh Schema on the MA and then check the Select Attributes (Show All) but no new attribute is shown

Any suggestions as to why