I searched many times, but there was no answer from MSFT or any other communities for this issue.
I have the Community edition 2019. Tabular model explorer is greyed out in the View->Toolbar->Other windows. I have no luck with VS 2017 EE as well, the same problem there too.
I could able to use the Import Datasource button on the Model menu and pull the source tables for building, however, Tabular model explorer and the data source folders are missing or not being able to use from a project perspective. Since the tabular model explorer is missing, I couldn't able to use the data transform window for each table and thus literally making a stop on development.
This is really annoying.
Here is VS 2019 system info
Microsoft Visual Studio Community 2019 Version 16.5.3 VisualStudio.16.Release/16.5.3+30002.166 Microsoft .NET Framework Version 4.7.03062
Installed Version: Community
SQL Server Analysis Services 15.0.19049.0 Microsoft SQL Server Analysis Services Designer Version 15.0.19049.0
SQL Server Data Tools 16.0.62003.05170 Microsoft SQL Server Data Tools
SQL Server Integration Services 15.0.2000.93 Microsoft SQL Server Integration Services Designer Version 15.0.2000.93
SQL Server Reporting Services 15.0.19049.0 Microsoft SQL Server Reporting Services Designers Version 15.0.19049.0
[Update 04/10/2020- Attached screenshot of the greyed out window menu] [SSAS Tabular Explorer Window greyed out]1