FF Checkbox Group randomly dropping options

I’m displaying a table of events where one of the columns is the grade level that the event is available for. I’m using FF Checkbox Group to manage it so that whoever is administering the data can simply select which grades are appropriate for each event.

I’m then trying to display the available grades in my table using the following syntax:

{if {camp_session_grades:selected option="1"}} 1,{/if}
{if {camp_session_grades:selected option="2"}} 2,{/if}
{if {camp_session_grades:selected option="3"}} 3,{/if}
{if {camp_session_grades:selected option="4"}} 4,{/if}
{if {camp_session_grades:selected option="5"}} 5,{/if}
{if {camp_session_grades:selected option="6"}} 6,{/if}
{if {camp_session_grades:selected option="7"}} 7,{/if}
{if {camp_session_grades:selected option="8"}} 8,{/if}
{if {camp_session_grades:selected option="9"}} 9,{/if}
{if {camp_session_grades:selected option="10"}} 10,{/if}
{if {camp_session_grades:selected option="11"}} 11,{/if}
{if {camp_session_grades:selected option="12"}} 12,{/if}

I’m running into a problem though where some events, even if grades are selected, don’t show any grade levels in the column. It is somewhat random and will sometimes show grades for an event and sometimes won’t show grades for that same event when refreshed. If I click on a detail of the event the grades are displayed.

Out of 185 total events, any given refresh of the page will have from 12 to 50 events not displaying their grade levels in the table.

What might be causing this?

thanks, brian