Just figured this out (I think).
Most cursors have an =
(equals sign) appended to them. For example: MzA=
This causes this syntax error in field expansion:
Syntax error "Expected ")" instead of '".' at character 79: comments.filter(stream).limit(10).summary(true).fields(id,like_count).after(NDA"
However, stripping the trailing =
resolves the syntax error and results seem to paginate as expected.