I'm pretty sure we ended up helping Lyle via email last week - it looks like the document got into a strange state that was causing this.
We filed a bug on the problem for further investigation, but in the meantime, the workaround was to copy everything and paste it into a new document. The new copy exported as he intended. (Looks like a bug, in other words, but the bug only affects the specific document he sent.)
This also seems like a good spot to mention that we post here as much as we can manage, but when things get busy, we may be off the forums for a while. If folks want to guarantee a response and get in touch as quickly as possible, emailing
omniplan@omnigroup.com and/or calling us at 800.315.6664 is strongly recommended.