As of today (2022-05-06), WebODM’s codebase has been updated with two fixes to PoTree that should prevent the much dreaded 3D Model/Point Cloud not showing issue.
To recap, the issue was introduced this past year and seemingly randomly makes it so PoTree starts empty, requiring the user to click the View Full Extent button to see the model.
If you’re running WebODM via Docker, make sure you grab your updates! Fixes for WebODM for Windows native will be out some point later through the Update menu.