In my monotubs wet substrate (coco/cow manure compost/vermiculite/straw) maintains high humidity for a long time. No need for FAE if using holes (mine are on the sides in two rows and filled with polyfill, aka pillow stuffing). Did you close the lid? How good of a seal did the lid have?

Recommend you move to pasteurized substrate soon if not planning to do so already. Much higher yields. Simply put the closed tub with wet substrate mix in the oven at low tremp till it gets to 150C (probe with baking thermometer), cool, and crumple up cakes into it at 50% volume.l while working next to a small personal HEPA air filtering unit. Cover and forget about it until harvest time.

I'm still trying to get through my flushes and it has been over a year.:d