When you are passing multiple years to the month filter the filter type of that month filter has to be a collection and not string. The string will work fine when it’s a single select.
Right now in your SQLQuery, it is specified as string only and that’s why it’s not working. Plz change it to the collection and it will work fine for multiple values
Hence change it from
<Parameter name="Year" type="String" default="2019"/>
<Parameter name="Year" type="Collection" default="2019"/>