All or Nothing needs to be activated when you use special values like -60002. Maybe try:
EQ(Peak Type,"Found")*CF+NEQ(Peak Type,"Found")*-1*60002 where CF is the name of your custom field above.
Another but longer way around this is to create two custom fields. Call one custom field LOQ (Peak, Real, Calculated and the formula is just CConst1). Enter into CConst1 of your processing method the lowest acceptable value for mg/tablet or your LOQ. Then create a second peak, real, calculated CF called Reported Assay or something like that and code it: GTE(Assay,LOQ)*Assay+LT(Assay,LOQ)*-1*60002. Tick all or nothing on this because of the -60002. Also tick missing peak.