System: Linux/MAC OS - reported issue.
If you have a few more changes in your .bashrc file, be aware that . ~/.fancy-git/prompt.sh must be the last line of it.
System: Linux (with KDE) - reported issue.
Maybe you could face an issue related to icons rendering when using Konsole on version 18.12.1.
An idea here is to update the Konsole to its latest version. So the problem might be solved ;)
System: MAC OS - reported issue.
As you can read there, the solution found is to brew install grep and adding /usr/local/opt/grep/libexec/gnubin to the PATH ahead of /usr/bin.
System: MAC OS - reported issue.
You can follow the steps as you did for grep, but this time, installing gnu-sed by running brew install gnu-sed.
If you've just upgraded it from v6.0.5 to a newest version, you might have seeing an error, because FancyGit can't find its configuration file.
You can fix that just by running fancygit --reset. It'll create a default configuration file and reset the FancyGit state.
System: Windows (WSL) - reported issue.
If you use Windows terminal, under WSL system, Fancy Git will not render icons and symbols properly.
In this case, you can use this font. This might solve the problem.