I had the same issue. Found it's due to a missing end jump in the sex scene script. If you go to game/adult.rpy (just open it in notepad or notepadd++ if you don't usually code), search for "label sumida02:" in the file. Right above it (should be around line 2570) is the end of the Emily sex scene, and the most elaborate path with kink is missing the jump command where it sends you back into the right part of the main story. To fix this, you can just copy the command from a previous 'end point' in the Emily scene (there's several), place it below the actual scene end and reload the game. If you're lazy and trust strangers on the internet, here's my edited version.
I've also found a bug in ch3, where the call to set Nierty's name uses the variable in the question. Since you obviously haven't answered that question, it crashes as it cannot find the variable '$nierty' yet (no shit, we're supposed to be setting that in the next screen). I've fixed the phrasing in the ep3 script to avoid that crash as well.
Once you're done testing, make sure to google 'Should I be downloading files from random people off the interwebz' and do some reading