Air carrier ground personnel reported the DG cargo pit size could not comply with the 15 passenger bags requirement for proper configuration. DG cargo was removed prior to departure.

Narrative

A few years ago; [the company] decided to remove the nesting systems out of the A320; this caused a few changes in how the ramp can load the airplane.1. It changed the location of the pit nets in 4/5/6.2. With the reduction of size in pit 4 the weight is still at 5348 lbs. No way one can fit that much in pit 4 without damaging the pit floor.3. With the reduction in pit 6 the new max weight is 882lbs.ZZZ had a flight a few weeks ago where the lead loaded the flight with 650 lbs. of hazmat and pitted in pit six. When they went to surround the Dangerous Goods (DG) with 15 bags the scanner would not allow them to add anymore weight to the pit once it approached 882 lbs. The lead was not able to understand why; since there wasn't any type of communication from the company on this change. I would also like to suggest that the scanner [and load planning software] should not allow anyone from submitting a load of DG in pit 6 if the weight of the bags will put it over the pit limits. The DG was removed off of the flight and the flight departed.The [job manuals] have not been updated.I was not the lead; but it appears not too many people inside the station understood what happened; I tried to explain it to the Lead and management and they had a hard time understanding what happened.