Alan, I not weddings but I do use it in the studio which is dark. No windows and only got two small tube lights above. Yesterday I tried AF-S and it seemed to be slower to focus. Yes I am now using BBF. Then a person on FM mentioned that on AF-S camera will confirm focus using contrast detect. The week before I used AF-C and it had worked better. Since these cameras can focus to -3EV (with f2 or faster glass), why even need a hot shot flash on the camera? Another thing is this mysterious 'Aperture Drive'. Now on A7rIV you can set it to 'focus'. What I hear is that it means camera focusses wide open. I didn't know Sony did not do this before. Even now there is not any detailed information as to how this works. I can see that even using my tamron 28-75mm f2.8, this menu option is available. Maybe I need to test it out to see if camera really is opening up for focusing or not.
Why don't you share the settings you use? Sony 85mm f1.8 focuses fast. For focusing, I would have picked Sony 35mm f1.8 instead of Sigma 35mm f1.2.
BTW - Sony has changed hot shoe again. My Plus IIs don't work at all on A7rIV. I thought it was my settings but I confirmed same settings and same Plus IIs work on A7rIII and A9 but not on A7rIV and A9II. Wish various review sites mentioned these important things. Now a days most reviewers are either in bed with the companies or for the click bait kind of stuff.