Remember that 12 dark must be just that. Your baby must have at least 12 hours absolute darkness, like DoeEyed says "No light leaks"
Also when flowering you will want low humidity, you don't want your buds to rot after all. I gather you have a bit of knowledge about growing to get this far and should be doing other bits correctly. I presume you have switched to the flowering nutes?, normally done 1 week into flowering.