Hi, Zelan. I was the assistant team lead for Beyond Yesterday's Grasp. Thank you so much for playing our VN.
The first thing you mentioned is not actually a glitch. The Surrender ending is not precluded by stopping Genevieve's killer—in fact, quite the opposite; it's impossible to get the Surrender ending without having done so. The transition between the ending and the preceding scene is indeed abrupt, however, and this will be addressed in a future update.
We've discovered from reader feedback that most people on track to get the true ending will instead get Surrender, mostly because they only choose options that acquiesce to Genevieve's demands. Without providing any spoilers in this space, I will say that your choices in the second and last sets of options are both pivotal to getting the true ending.
Thanks for commenting! I hope you'll get to see the other endings as well.