Seems to be a dialogue bug.

Talking to the ferryman after crossing the bridge. There are four selectable speech options but 3 of them don't do anything. The 4th one says "positive" and goes into its speech but goes right back to where it started.

It soft locks the game for me because I can't progress any of the interaction.

EDIT:

Seems like its all dialogues with differences. Added screen shot.

Mods using:

Fallout London - See Through Scopes
Place Everywhere
See Through Scopes
Reverb and Ambiance Overhaul
Workshop Rearranged
xSE PluginPreloader F4
TRUBY9 ULTRAWIDESCREEN LevelUpMenuEx compatibility fix
Classic Holstered Weapons System (CHW)
Buffout 4
ENB series