Who can view participant invoices
Depending on the organisation you are "Using as" in the admin area will determine what invoices you can view in a participant's profile.
Invoices will only appear when you are "Using as" an organisation that has a fee line item within the invoice (i.e. the organisation appears within the invoice with a fee).
If you cannot locate an invoice, and you have admin access to "Use as" multiple organisations, try to change the organisation you are "Using as" to the association or club the participant has registered to.