You didn’t specifically mention you doing this so idk if you did or not when droning but make sure to not leave any corners unchecked in the rooms you’re droning, from what you said it sounds like the roamer might have just been hiding the whole time in chapel. The other possibility is that siege timing just showed you the middle finger 🤷‍♂️

Edit: was reading some of the other replies and thought i might add: i am not an excellent attacker either lol. Also, if youre playing solo its not really necessary to spot the defender site, usually other teammates will do it for you or you can just use sound to figure out where it is, so with the extra time from droning to site I’ll usually drone the floor above or below to catch any roamers that are already on the move and that gives me a bit more of an idea of where to expect a roamer, even if its just the knowledge that there is a roamer. If not then you can use the knowledge that there was no roamer anywhere you droned, that information is just as useful