Second Apiguard tray goes in tomorrow — queen's gone off lay, is that expected mid-treatment?

Six seasons in Flanders and first time using Apiguard (formic every other year until now, fancied a change while temps suit thymol). First tray went on two weeks ago, second tray due tomorrow per the label. Did a quick peek while topping up feed and my best queen appears to be completely off lay — plenty of emerging brood but no eggs and only a small patch of larvae. The whole colony also smells like a cough-sweet factory and they've moved stores around oddly, gap in the middle of the brood nest. Before I panic: is going off lay a known thymol side-effect? Do I still put tray two in on schedule, or give her a break? And the accidental brood break this causes — I've heard people say it actually helps the treatment work better since mites can't hide in capped cells. True, or wishful thinking from people whose queens stopped laying?