It appears that the soul bonus does not calculate correctly in Quest matches when the soul cap is not met, when playing with a team with multiple necromancy traits. I have a team with three troops that have the necromancy trait active. The soul cap shows as 100, but if I don't get exactly 100 souls, the bonus at the end of the round is calculating wrong.
First match, 85 souls were collected, but only 161 were awarded. My current bonus should have been 315%, but the awarded souls were only 189%. The next match, 80 souls were collected, and 101 awarded, this time 126%. The third match, 100 souls were collected, and 315 souls were awarded.
All matches were played in quest mode, under Warlord II difficulty, on the PS4.
This does not appear to happen with normal teams that don't have necromancy traited troops, as those have been calculating correctly.