also secreats and frozeta mod, i forgot about it, all these mods makes basic belt capacity 0, so basic stacking tech makes it 1 , than 2 standart upgrades makes it to 3, than secretas's research make it 4, than vesta makes it 5, and ur stacking trch also adds one belt capacity, which must make it 6 (actually it doesnt, idk maybe thats in my modded build, if u cant replicate this issue i will give u savefile, maybe some of my mods messes up with researches) but stack inserters still use 5 stack like they didnt see stacking research in ur mod (maybe thats cause ur stacking research didnt connected to game's standart stacking belt capacity tech tree so maybe reaarange it into 2 spearate researches, like 1 research is alt stack inseter and second being +1 belt stack, which will be conncted to basic game belt staking tech's)