If using the Mobile App technique did not work for you, try going into a Channel Information Screen and see if you can locate and remove the app. Then restart the Roku device and install the app from the device, not the online Streaming Store.
1. Go to the Home Screen. Using Roku Remote, press Home at least 3x, then Up 2x, then left, right, left, right, left.
2. After the Channel information Screen appears, scroll down and find the installed app that is not showing on your Home Screen and press OK, then select Remove.
3. Press Home to exit menu screen and then perform a System Restart on the device.
4. Use the Search feature from the Home Screen to install the app. (do not use online streaming store). Hopefully you can now see your missing app on the Home Screen.
Yeah that Konami-code ass trick didn't do anything either. Anyone got any suggestions that actually, y'know, work?
Unfortunately, the mobile app technique and the Channel Information "konami" trick are the only two workarounds currently working to restore visibility of a channel/app back to the Home Screen until Roku addresses this bug. (short of a factory-reset that has helped others).
The channels/apps not being shown are random. (and occur for different users and different devices). I have found that installing from the online Streaming Store leads to more "invisible" apps being installed (but incapable of being seen) than when I install them from the device. However, I have run into a couple that I installed from the device that were also invisible.
Of the ones I installed from both the device and online, I found they all were able to be removed via the Roku Remote Channel Information Screen and installed properly from the device after a System Restart and a subsequent device install.
Unfortunately, I have seen little recognition from Roku that this bug exists, as evidenced by their suggested fixes to impacted users. I would just try the recommended fixes again and see if you missed something in the operations/techniques that may have made them unsuccessful for you.
Here is a recent posting with the mobile app technique explained which was successful for a few users https://community.roku.com/t5/Channels-viewing/YouTube-app-not-on-homescreen/m-p/1032263#M181173
As a last resort, you could try the Factory Reset procedure. https://support.roku.com/article/208757008