Custom field of type CheckboxSet has always multiple values. It cannot be used with type INT in database, or you get an error for wrong integer type '' if no value is selected. However, in the converter you set the field to the type INT if is not defined as multiple:

				case 'CheckboxSet':
				case 'Member':
					if ( $data['multiple'] )
					{
						$columnDefinition['type']	= 'TEXT';
					}
					else
					{
						$columnDefinition['type']	= 'INT';
						$columnDefinition['length']	= 10;
					}
					break;

It is not possible to save a record with field type CheckboxSet that is defined as INT.

The type should be moved down to:

				case 'CheckboxSet':   <-------------
				case 'TextArea':
				case 'Upload':
				case 'Address':
				case 'Codemirror':
				case 'Select':
				case 'Youtube':
				case 'Spotify':
				case 'Soundcloud':
				case 'Item':
					$columnDefinition['type'] = 'TEXT';
					break;

 

Edited February 16, 20214 yr by Sonya*

I've raised your concern internally for further investigation. Thanks!