Ng2-smart-table selectText issue in editor-config for dropdown (Add,Edit)

Hi...
I have tried using ng2 smart table to display the data but the issue is on dropdown to be displayed with placeholder (used default attribute "selectText" in editor -config) on clicking Add New and Edit Action.
Placeholder not working while clicking the Add New action and Edit action on select field.

///Typescript
this.settings = {
edit: {
editButtonContent: '',
confirmSave: true,
},
delete: {
deleteButtonContent: '',
confirmDelete: true,
},
actions: {
position: 'left',
}, attr: {
class: 'table'
},
add: {
confirmCreate: true,
addButtonContent: 'add new', this: this.checking()
},
columns: {
employeeFirstName: {
title: 'First Name*',

},
employeeLastName: {
title: 'Last Name',
},
employeeEmail: {
title: 'Email*',
editable: false
},
role: {
title: 'Role*',
type: 'html',
valuePrepareFunction: (cell, row, companyList) => {

// this.placeholder();
let bn = this.userRoleList.find(x => x.value === cell);
if (bn) {
return bn.title;
}
else {

return cell;
}
},
editor: {
type: 'list',
config: {

selectText: 'Select',
list: this.userRoleList

}
}
},
ageGroup: {
title: 'Age Group*',
type: 'html',
valuePrepareFunction: (cell, row, companyList) => {
let bn = this.ageGroupList.find(x => x.value === cell);
if (bn) {
return bn.title;
}
else {
return cell;
}
},

editor: {
type: 'list',

config: {
placeholder: 'hello',
selectText: 'Select ID',
list: this.ageGroupList
// list: this.industriesList
}
}
},
experience: {
title: 'Employer Experience*',
type: 'html',
valuePrepareFunction: (cell, row, companyList) => {
let bn = this.employerExpList.find(x => x.value === cell);
if (bn) {
return bn.title;
}
else {
return cell;
}
},
editor: {
type: 'list',
config: {
selectText: 'Select',
list: this.employerExpList

}
}

},
gender: {
title: 'Gender*',
type: 'html',
valuePrepareFunction: (cell, row, companyList) => {
let bn = this.genderList.find(x => x.value === cell);
if (bn) {
return bn.title;
}
else {
return cell;
}
},
editor: {
type: 'list',
config: {
selectText: 'Select',
list: this.genderList

}
}
}

},
};