Overlays aren't working offline
The overlays need Elevation Data to work without signal. If they work when you're connected but not when you're offline, here's what to check:
Check the area is downloaded
Make sure the area you're looking at is inside one of your offline maps. Tap your profile picture at the top right of the Guide tab to open your account, then tap Offline Maps to see what you've downloaded.

Check Elevation Data was included
This is the most common cause. Resort downloads include elevation data automatically. For a backcountry region, check that Elevation Data was included. If it wasn't, download the area again with it turned on, while you're connected to WiFi.

If you downloaded a resort before November 10th, download it again while you're on WiFi to make sure it includes elevation data.