The lines under shadow-exclude need to be separated by commas as indicated. Plank shadow was due to these lines
"class_g = 'wbar'",
"class_g = 'Conky'"
"class_g = 'Synapse'",
while the correct ones are
"class_g = 'wbar'",
"class_g = 'Synapse'",
"class_g = 'Conky'"