in reading the help entry, it would, at first glance, appear that your code is correct, but I think there is a missing piece.
usually, in CR, the condFld is a grouping condition. Does your report group the data based on the ManualReview field? If it doesn't, this probably won't work. If it is, then I am not sure why it isn't working.
you can probably set up a running total, but that is not my forte, but DBlanks. I would set up variables and increment them as needed. something like:
SOP30200.SOPNUMBE}, {spxSalesDocument.ufManualReview}, "Yes")
shared stringvar invoices;
shared numbervar invoiceCount;
if instr(invoices,{SOP30200.SOPNUMBE} + "|") = 0 AND {spxSalesDocument.ufManualReview} THEN
invoiceCount := InvoiceCount + 1;
invoices := invoices + {SOP30200.SOPNUMBE} + "|")
"" //hides all the formula results
HTH