I have made 1-(2,5-dimethoxyphenyl)-2-nitropropene with methylamine, cyclohexylamine, n-Butylamine and ammonium acetate and even though the yields are different the product is the correct one. Perhaps the LAH reduction didn't go to completion. Therefore the need of more water/IPA to quench the LAH. If so, the oxime and N-OH-2,5-DMA are major products.
Edit
I looked this up right after I posted the answer to you.
Varma and Kabalka1 says that when 1-(2,5-dimethoxyphenyl)-2-nitropropene is made from 2,5-DMBA, nitroethane, GAA and ammonium acetate three diffrent products can be obtained depending on the ratios of the reactants and reaction time. When 2,5-DMBA/EtNO2/GAA ratio of 1:1,5:0,8 is used a 70% yield of 1-(2,5-dimethoxyphenyl)-2-nitropropene was recovered. At a reactant ratio of 1:3:2, the major product was 2,5-dimethoxybenzonitrile (62%), and at a ratio of 1:40::8, with extended reflux time, the major product was 3-(2,5-dimethoxyphenyl)-5-methyl-1,2,4-oxadiazole (24%). Using nitromethane, the only product is the nitrostyrene despite the reaction time and ratios. Perhaps something similar can happen when using methylamine as catalyst?
1. Organic preparations and procedures int. 19 (4-5), 283-328 (1987)