Services Views not exposing thumbnail image url
It's a bit unclear what you have in your view, but here are some suggestions:


Make sure you have Formatter set to "Image URL", and the "Image Style" set to the specific style (ie thumbnail)
Ensure that you actually have some data for your filter. "No Results Behavior" may have "Hide if empty", which would omit this field in your response if it's not set.
Enable showing the query and results for the view to at least check that the return data contains the value that you expect (admin/structure/views/settings -> [] show performance statistics)
Check that your contextual filter is not obfuscating something - remove the args[0]=1
Ensure that the normal Page response for the view displays a value for the thumbnail field, by going to the "path" that you've defined for the view.