This seems to be 30% to 50% chance to happen when starting Orion.

In the above screenshot only "Kagi Assistant" is shown. Sometimes no tab is shown. But you can tell there are tabs base on the "+" button position.
This can happen on all saved windows. Sometimes all the saved windows, sometimes only the first one.
I am using "Switch Saved Windows in place". When I cycle all the saved windows once, the issue does fix itself.
Not sure if this happen if "Switch Saved Windows in place" is not use.
This should not happen.
Version 0.99.136.3.1-rc (WebKit 623.1.8.0.0)
Tahoe (26)