How to open an installed app (not from googe play store) on android 7.1.1

[AC Question]

Our company has an app and we consistently test new versions. Now I got upgraded to android 7.1.1. I can download the new (not google plag app version) and install it, but I cannot open it. No icon appears. I tried to do it via launcher but it didn't help.
Maybe some nows a solution?

 

[B. Diddy]

Welcome to Android Central! You downloaded it as an apk file and tapped the file to install it?

 

[VitoLTU]

Yes. I did everything the usual way, developers sent me the apk, I installed it and after that I couldn't press open, The app icon is nowhere to be found.

 

[B. Diddy]

Did you uninstall the old version before installing this version?

Since you're testing these new versions, have you already given this feedback to the developer? Perhaps it's a bug that others have noticed as well that the dev needs to address.