The standard melodic packages use python 2, so using python 3 here was causing errors when trying to import tf. Compiling tf from source with python 3 worked, but then the other system packages (e.g. gazebo) were crashing because they wanted the python 2 version.
The standard melodic packages use python 2, so using python 3 here was causing errors when trying to import tf. Compiling tf from source with python 3 worked, but then the other system packages (e.g. gazebo) were crashing because they wanted the python 2 version.