This is related to Pipeline Rule not able to parse double from string field
It appears there are some very non-intuitive limitations for naming fields. According to this, names must be single-quoted if they include a dash. In the example above, there was a problem if the name had the suffix _converted appended.
Would be nice if the docs clearly stated the syntax of valid field names so these issues can be avoided. They are quite hard to debug, because there is no clue that it’s the name which is causing the problem.