If you haven't figured it out yet: you need to reclaim Castle Whitemoon to the West of Oakshire first. (And get the succubus companion). Before continuing the main quest. Whitemoon is essentially your home base throughout the game.
That hitbox is always finicky. You're not the first one to have problems with it. (Myself included). If you still haven't gotten it, exit the cave, and then retry from every angle you can. Even outside what you think might not be the hitbox. If that still doesn't work, you can post your save file here, and I can get you past it.
Try out my save file
here. It's right before the Tilan DLC starts, and it should have the unlocked gallery. Just be mindful there are some bugs in the gallery that will crash the game, especially for the female scenes in Oakshire and Summerdge that I've seen so far. (Some of the Carys Male scenes too). Also the Tilan DLC scenes are not updated in the gallery yet.
Redkinght hasn't fixed all the bugs in the gallery yet. They are a forum moderator here on F95 and Kaliyo's Discord. They're not actually one of the main developers of the game. More of a fan, with enough bravery and patience, to try and work through several years worth of the spaghetti code in Roundscape's files. So expect some delays. I would recommend using open save slots during the DLC. In order to save right before a Tilan sex scene. At least until a new patch is made for the game.
If you need to there is a cheat code for the Skip Combat Skill. It's 2931. Or upgrade the shit out of your weapons, like Eraser and Aetherius, and get dual wielding. If a Templar use Censure. Or if you want overkill save edit yourself the Soul Sword.
Make sure you have the 5.0B patch installed. The 5.0 game version had a bug where the emissary never showed up in the Castle to start the new DLC quest.
If you still haven't gotten her to stay, or haven't save edited it yourself. I wrote a guide sometime ago for Male players
here.
In the south of Ornesse, there is a building with a guard stationed. You can use the empathy perk to get into the building, go through the sewers, or pick a lock.
The quest log has been bugged for awhile. It shouldn't stop at 20, it's just a lot of side quests don't show up or update properly. It used to be worse, and the devs have worked on it over the past couple years. (In different patches) It still has bugs though.
You can always try and use Redknight's pdf walkthrough for Roundscape. It hasn't been update for a few patches now, but it has most of the quest, side quests, and possible sex scenes/events listed if you need to check them/jog your memory.
For Fem MCs check out my post
here. For Male MCs: Meredith, Clawyn, Ruksana, Tiah, Jenda and Jerrah, and Abby. You can also has sex with a pregnant Lizagon, dissatisfied with her husband, if you're into that sort of thing.