Impossible to add new fields - bad INSERT

I already had a CCK content type created with three fields, then installed 4.7--1.3 and carried out update. At this point, I tried to add a new field to a CCK content type. Result, the field is created (the message says that the field is created), but it is not possible to add the field to a content type. The reason appears to be this error message:

Field 'display_settings' doesn't have a default value query: _content_admin_field_add_existing_submit INSERT INTO node_field_instance (field_name, type_name, weight, label, widget_type, widget_settings, description) VALUES ('field_cover', 'content_test', 0, 'Cover', 'image', 'a:6:{s:14:\"max_resolution\";s:1:\"0\";s:10:\"image_path\";s:0:\"\";s:10:\"custom_alt\";i:0;s:12:\"custom_title\";i:1;s:13:\"teaser_preset\";N;s:11:\"body_preset\";N;}', '') in C:\Apache\Apache2\htdocs\drupal-4.7.4\includes\database.mysql.inc on line 121.

In other words, when the new field is created there is no value given for the "display_settings" column in node_field_instance. As a workaround, I tried allowing NULL on this column - and now everything seems to work.

The only problem is, there does not seem to be any way of either using or getting rid of the fields I created before finding the workaround. They appear in the "display fields" list, but not in the "manage fields" list, nor do they appear when you try to create content. Nor does this appear to be fixed in 1.4