Hi David,
You may need to go into Reporting Manager and under 'Flex Field Reporting' select 'retrieve flexible fields metadata for reporting'. Once this is ran and you have some data (i.e. the dataload has ran) you should be able to find the field within the report. If you cannot find the field on Pivot Layout in Analysis you might need to check you are on 'Available Fields' and not 'Available Hierarchies' which is the default.
Kind Regards,
Mat