Summary Report Issues

Starting with fields:

Group Types, VL:Private or Group;

Rides Types, VL: 30min, 60min, etc., for example;

Count_field for each Ride = "1"; and

Sum_calc = Summary of "Count_field"

I have built a summary report layout with the intention of Grouped data sorted by Ride Types that includes:

A general grouping by category of each of the two Ride Types including a heading stating either Private or Group;

A group of each Rides associated with one of the two Ride Types, positioned under one of the two headings, listing the various Rides and its corresponding subtotal;

A subtotal for each of the two Ride Types, Private and Group;

and

A grand total comprising the two subtotals.

Aside from labels, header and footers I have a:

First subsummary sorted by "Group Type" with Group Type

Second subsummary sorted "Ride Type" with Ride Type and Sum_calc

Nothing in the body

A Third subsummary sorted by "Group Type" and Sum_calc

A Trailing Grand Summary with only Sum_calc.

I have seen this layout work (and had it witnessed) and see, within minutes of switching to other layouts and back, only partially displayed the data;

I have rebuilt this layout to only repeat my experience of it working initially and then failing.

Any ideas on what could be causing this?