Rapid Setup premature detonation
The Rapid Setup ability only applies charges and combo points when the graphic of the selected charge strikes the target. This problem causes the detonate ability to only detonate a single charge wich is placed when the charge is selected, prior to the target being struck with the graphical effect. This also has the side effect of preventing Rapid setup from actually habing its effect of adding the additional charges.
Temporary solution is to pause hitting the detonate ability until the graphic strikes the target and the other combo points are active, or simply throw a frag bomb as it has the same travel time and will strike after rapid setups full effect applies.
Recommended fix for Devs would be to cause the 5 charges and combo points to be applied at the time the graphic strikes the target without a single charge/combo point hitting it first. This would prevent the Detonate ability from becoming active and "premature detonation" from becoming a dps loss.