I've tested iPhone export of a simple native app, using the stable version (currently 18.104.22.168), and encountered no problems.
Are you using the same version? If not, please upgrade - see http://www.tersus.com/#Id=239.
If your studio is up-to-date, please check whether this occurs for all apps or for a specific one - try creating a new native app and exporting it as-is.
If the error occurs in specific apps, can you export one and attach it to a post in reply?
If the error occurs for all native apps, check the studio log for any relevant errors (Help > About Tersus Studio > Installation Details > Configuration > View Error Log).
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