I have the same problem and I've been trying to chase it on Valve's Github.
https://github.com/ValveSoftware/Source ... ssues/1559The gist is, I think I managed to get it working for HL2, but getting it to export for EP2 doesn't seem to work and, unfortunately, I didn't have success copying the scenes.image export from HL2 back to EP2. It contains the data, but the scene is consistently "missing" in-game.
It seems to me that this aspect of Faceposer wasn't updated to account for the change in file location. Naturally, Valve seems to have forgotten about this - like everything else that Steampipe broke.