Why this button won’t show up on some devices?

Example

This image is what it looks like in the activity in Android Studio. This is not the main activity.

override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_game_creation)
        hideSystemUI()

    }

(Image belows create script)

/** Called when the user taps the Create button  */
    fun gameClick(view: View) {
        val intent = Intent(this, GameCreation::class.java)
        startActivity(intent)
    }

(Main activity script that launches the activity)

The start button doesn’t show up on some devices, the rest have a blank button with no “START” text on it.

No text shows up either from my testing, how can I fix this?

Edit: Layout

Answer

I can’t explain why the button would be completely gone on some devices, but the reason it has no text is that you haven’t set it to have any text. You have:

tools:text="START"

The word tools means that property is only for visualization purposes in Android Studio. This is commonly used for views that have dynamic text that you plan to set in your application code.

In the design editor, view properties that have been set using tool have a little wrench icon next to them. You can find the property with the same name but no wrench icon to set the actual text that will appear when the layout is loaded in the app. Here’s the difference:

enter image description here