A report on the
DOT&E testing of the ACV 1.1 mentions the following:
"The ACV threshold requirement for quantity of personnel carried is 3 crewmen and 10 embarked infantry with full combat loads, including 2 days of supply and combat essential equipment. The ACV accommodated 3 crew and 13 embarked infantry, but accommodations were cramped, which made it difficult for infantry to egress from the vehicle.", and
"Infantry troop commanders had difficulty moving between the hatch and their seat. Aligning the hatch with the seat could allow the commanders to stand up with their heads out of the hatch, but then drop down inside the vehicle to operate the troop commander’s video display screen, talk to their marines, and prevent exposure to incoming fire."
This suggests that, IMHO, the interior was designed to meet the requirement (3+10) but was tested with the AAV extant manning (3+13), hence the difficulty with egress (and presumably ingress) which is not good on a 2 way firing range.
Perhaps the biggest issue with the ACV 1.1, under testing at the time was "during the OA (operational evaluation/assessment), the BAE vehicles demonstrated an MTBOMF of 24.9 hours (50 OMFs during 1,242.6 hours of mission time), which was less than the 58-hour MTBOMF growth curve point estimate. The RWS, which is government-furnished equipment, was the source of the largest number of OMFs (operational mission failures)".