While trying to build a on the XL Fuel tank when I try to add additional engines to the top in a 5 engine pattern, I had a decoupler on the bottom tank and then a engine plate on the upper with one engine from the M category and 4 from the S category it will align center but will only generate a fairing around the center M engine. When I tried to change tactics and apply 6 S engines the upper stack would not snap to center even when Snap was disabled. After this I attempted to utilize fairings, but the fairings have to be applied in a overly specific way and would break the rocket on liftoff
Let me know if I can provide more details. some of this could be a symptom of being new to the series, I'm happy to admit that but this is an incredibly cumbersome process and makes me feel like I wasted an hour and a half of my time and the only thing I got from it was frustration.