Did you add an organic solvent too during the work-up? You don't mention it... generally for a Fischer I would add a decent amount of ethyl acetate and water, enough that the methanol doesn't form any emulsions. Separate the layers, then wash the organic layer again with NaHCO3 to remove any unreacted starting material as the acetate.
It's not clear to me what the precipitate is - the product should be an oil at RT so not that. I guess it could be unreacted SM since its aqueous solubility is low, so you may have triturated it out of the methanol solution by adding water. There isnt any plausible way you could have formed acetylsalicyclic acid...