I'm using Ubuntu 18.04 and I have the following issue.
I can't find many apps using dock search but it's already installed.
ex: I've searched for calculator
I opened software center and calculator already installed.
When I opened calculator from it I found that icon is missed on the dock
I also opened ~/.local/share/applications and I found desktops entries for chrome only.
Note: the I have the issue with manually installed apps from software center like vscode or using apt like terminator.
It is ok if you have only chrome entries in your .local/share/applications directory.
In the directory /usr/share/applications you should find your files.
A good description can be found on on this link