This is a long standing annoying bug which is related to apple events in macOS. Operating system can sometimes end up in a bad state where apple events are not being delivered to Finder. This prevents TotalFinder from injecting code into Finder.

I wrote a support article at https://totalfinder.binaryage.com/injection-troubles

TotalFinder does not launch

darwin May 25, 2015, 9:03am 4

Ah :-/ Can you please follow this post and report Console.app log?