Even with dry reaction, you might need to extract the solids multiple times to get all of the product out. Extractions of dry materials are slow and poor yielding in some cases. That would be my first guess as to low yield. I also agree that hydrolysis of TsCl might cause side reactions, but not sure of it.
I have to agree that in some cases solvent reactions are more easily reproduced, but partly because the details are usually give clearly. In the case of a no solvent reaction, there may be factors that are not clearly described, like how well the compounds were ground, how hard they mixed, how long, etc.