GameObjects appearing in Editor but not in Build (disappearing) Problem.

Check the runtime logs. Google for where they are located on your machine.

You’d be looking for things like exceptions or errors in the log.

OR if this is just a UI Anchoring issue, here’s some notes:

Here are some notes on UI Anchoring, Scaling, CanvasScaler, etc:

Usually you need to choose a suitable ScaleMode and MatchMode in the Canvas Scaler and stick with it 100%. Generally if you change those settings you will often need to redo your UI entirely.

I also use this CanvasScalerOrientationDriver utility to make sharing UI for Landscape / Portrait easier. Read what it does carefully.