The detail section of your form goes completely blank if both:
1) There are no records to display, and
2) No new records can be added.
#1 could be caused by a table with no records, a query that returns no
records, a Filter that returns no records, etc.
#2 could be caused by a read-only source query (i.e. you cannot add records
to the query either), by setting the form's AllowAdditions property to No,
by using a read-only source (CD, network share, etc), or permissions.