question

This is a bug. As @Jason Lightfoot noted, the Experimenter is flagging the columns as REAL when they should be flagged as TEXT. SQLite allows data to not match the declared type, and so the text data is added to the table correctly. However, PowerBI probably depends on the column type to determine how to show data.

Don't know very much about PowerBI, but I wonder if there is a way to tell PowerBI to treat those columns as text, to sort of override the behavior. But I'm not sure.

Another thing you can try is to fix the column declaration in the file. You can do this with the following code:

/**Custom Code*/
Object current = Model.find("Tools/Experimenter");

Database.Connection db = function_s(current, "getDBConnection");
int shouldDisconnect = 0;
if (!db.isConnected) {
    int connected = db.connect();
    if (!connected) {
        return 0;
    }
    shouldDisconnect = 1;
}

db.query("PRAGMA foreign_keys=OFF");
db.query("BEGIN");


// create a new table with the correct scheme
string createStmt = "CREATE TABLE new_table (\
      task_id INT REFERENCES tasks(id) ON DELETE CASCADE\
    , \"Date\" REAL\
    , \"Linha\" TEXT\
    , \"MetricName\" TEXT\
    , \"MetricValue\" REAL\
    )";
    
db.query(createStmt);

// Copy all the data from the old to the new
db.query("INSERT INTO new_table SELECT * FROM \"/CalculatedTable1\"");
// Drop the old
db.query("DROP TABLE \"/CalculatedTable1\"");
// Rename the new
db.query("ALTER TABLE new_table RENAME TO \"/CalculatedTable1\"");

db.query("COMMIT");
db.query("PRAGMA foreign_keys=ON");

if (shouldDisconnect) {
    db.disconnect();
}

The code essentially creates a new table with the correct column definitions, copies the data from the old table into it, drops the old table, and renames the new table.

You'll have to run this in a script window. I tried putting it in the "On End of Job" trigger, but I think there's a timing issue; there's an exception with trying to drop the CalculatedTable1 table. I suspect it hasn't finished writing that table to the disk yet.