API Migration from 5.4 to 6.4.3.0 not working

SwagMigrationAssistant says that everything is migrated and it is now indexing. However, there is only one product migrated (out of 550), translations are made into categories. All is mess.

From the log:

[warning] SWAG_MIGRATION_CANNOT_CONVERT_CHILD_PRODUCT_MEDIA_ENTITY

[error] SWAG_MIGRATION_RUN_EXCEPTION
An exception occurred
Entity: number_range, sourceId: e298cf7965ef4508996b4b75b1ab5723
An exception occurred while executing ‚INSERT INTO number_range_sales_channel (id, number_range_id, sales_channel_id, number_range_type_id, created_at) VALUES (‚OhLnd:‘,‚BlI[\58‘,‚DG\Z;‘,‚a% L&g‘,‚2021-08-15 09:19:32.493‘);‘:SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (sw6.number_range_sales_channel, CONSTRAINT fk.number_range_sales_channel.sales_channel_id FOREIGN KEY (sales_channel_id) REFERENCES sales_channel (id) ON DELETE CASCADE ON UPDATE C)

[error] SWAG_MIGRATION__WRITE_EXCEPTION_OCCURRED
A write exception has occurred
{
„entity“: „main_variant_relation“,
„dataId“: „21f4bf04f8c3415f976a942a920efee7“,
„error“: {
„code“: „c1051bb4-d103-4f74-8988-acbcafc7fdc3“,
„status“: „400“,
„detail“: „This value should not be blank.“,
„template“: „This value should not be blank.“,
„meta“: {
„parameters“: {
„{{ value }}“: „null“
}
},
„source“: {
„pointer“: „/22/translations/2fbb5fe2e29a4d70aa5854ce7ce3e20b/name“
}
}
}