Thank you Beverly for giving me credit for helping you resolve your problem with the zone measurement.
I'd like to offer an additional clarification. You mentioned that you had been turning the zone heights to 0 in order to avoid seeing them in 3D. You don't have to do this. The View menu > Elements in 3D View > Filter Elements in 3D dialog allows you to turn on or off the visualization of Zones in 3D. The default is for Zones to be off; you must have turned them on.
Views in the View Map record this setting, so if you created or revised your 3D Views with Zones turned on, they will remember it. This is particularly useful when you WANT to show zones for some sort of presentation or study.
Simply making this change once will reset it for all subsequent 3D viewing, UNLESS you have one or more saved 3D Views. When you double-click a saved 3D View, it reinstates the settings that were in effect at the time it was created (or last updated).
If you have any saved 3D Views in the View Map, activate each one at a time, and if necessary (and desired), turn off the Zones in 3D using the Filter Elements dialog, then use the View Settings - "Get Current Window's Settings" button to update the View so it is set the way you like.
Eric