Android application icon not showing up

I would like to elaborate on the answers of @Britton Pentakill and @arnav bhartiya because I could solve my problem using their answers. I added more actions on my MainActivity because Android Studio was complaining that "App not indexable by Google" and I also wanted it to be indexable.

Wrong AndroidManifest.xml:

<intent-filter>
  <action android:name="android.intent.action.MAIN"/>
  <category android:name="android.intent.category.LAUNCHER"/>
  <action android:name="android.intent.action.SEND"/>
  <action android:name="android.intent.action.VIEW"/>
  <category android:name="android.intent.category.BROWSABLE"/>
  <data android:scheme="https"
        android:host="siara.cc"
        android:pathPrefix="/CrossCalc" />
 </intent-filter>

So when I published my app, people could not find my App Icon on their device, no Open button after installing on Play console, even if it did pass review and published on play store (it took 7 days).

Then when I read their answers, I corrected and now I am able to see the icon for opening my app:

Correct:

<intent-filter>
  <action android:name="android.intent.action.MAIN"/>
  <category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
<intent-filter>
  <action android:name="android.intent.action.VIEW"/>
  <category android:name="android.intent.category.DEFAULT"/>
  <category android:name="android.intent.category.BROWSABLE"/>
  <data
    android:scheme="https"
    android:host="siara.cc"
    android:pathPrefix="/CrossCalc"/>
</intent-filter>

Notice Win Myo Htet's comment on the accepted answer. He solved my problem.

Jems since your answer has so much vote, can you add the following pointer too: Make sure that intent-filter for MAIN and LAUNCHER is not mixed with other intent-filter. – Win Myo Htet Dec 6 '15 at 5:47

"mixed" being the keyword. I had intent in my AndroidManifest.xml file that was there to prevent all file types from being available in file selects. While it began with the second answer's solution, it contained the extra intent for the file selects. This prevented Android from installing my icons when installing the app. I wanted to post this in case anyone else ran into this issue since Win My Htet's brilliant advice could easily be missed since it is essentially one word "mixed"

1. Make sure the icon is stored with the name icon.png in those folders.
2. Make sure android has a drawable/icon resource. Check this by looking at your gen/R.java file and seeing public static final int icon = 0x.... in the drawable inner class.
3. Try cleaning your project build and uninstalling any existing version of your app from your phone/emulator and then reinstall the new version.