If you have multiple extended choice parameters in your job, when you go back in to the configure page after saving only the last job has all the options visible. Clicking on the simple/complex parameter radio buttons makes the info show but it should be visible initially.

See attachments for examples:
configSnippet.xml - config.xml of the job I've seen this on - 2 extended choice parameters
screenshot.png - the 2 params show but only one has the config options visible