do they have other vertical surfaces to lay on other than the glass wall? you could try to give them a cone to lay their eggs on instead, and that way u can also cage the eggs with mesh to prevent them from eating them before they become wrigglers (but they can still fan them). without a cone my guys will lay on the vertical glass surface or the logs, but they prefer the cone if its available
i had a pair who ate their eggs every time they spawned... then i caged the eggs and let them hatch into wrigglers and removed the cage so they could practice with the older fry. they stopped eating their eggs after that and i didnt need the cage any longer
here is a pic of a cone i ordered from a lady on simply discus. they r beautiful handmade works of art and the fish love them!