Switch from Direct Lake to Import Mode

The warning happens because it requires a refresh operation since it is still directlake. Sorry for misunderstanding here. To convert the your model to Import mode you could use the following c# code through Tabular Editor after connecting to your model. After running it you should use Model --> Deploy option to deploy the newly converted model as a new model in a workspace.

using System.Reflection;

const string mImportTemplate =
@"let
Source = DatabaseQuery,
Data = Source{{[Schema=""{0}"",Item=""{1}""]}}[Data]
in
Data";

foreach (var table in Model.Tables)
{
if (table.Partitions.Count != 1) continue;

var partition = table.Partitions[0];
if (partition.Mode != ModeType.DirectLake) continue;

var pMetadataObjct =
typeof(Partition).GetProperty(
"MetadataObject",
BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.DeclaredOnly);

var tomPartition =
pMetadataObjct.GetValue(partition)
as Microsoft.AnalysisServices.Tabular.Partition;

var tomPartitionSource =
tomPartition.Source
as Microsoft.AnalysisServices.Tabular.EntityPartitionSource;

if (tomPartitionSource == null) continue;

var schemaName = tomPartitionSource.SchemaName;
var tableName = tomPartitionSource.EntityName;

var partitionName = partition.Name;
partition.Name += "_old";

table.AddMPartition(
partitionName,
string.Format(mImportTemplate, schemaName, tableName));

partition.Delete();
}

Model.Collation = null;
Model.DefaultMode = ModeType.Import;
Model.RemoveAnnotation("TabularEditor_DirectLake");