Although unusual, it is quite common for one or both of the parents to stop defending the eggs/fry. Especially on the first few lays when the parents are first maturing to the scene. This will normally result in the eggs going bad or being eaten, but it's not always the case. In fact I have a breeding pair of Electric Blue Acara, but the strange thing about this pair is that the male seems to leave the female to it once the deed is done and they've had multiple spawns. Various factors can have an affect on this though, I'm under the impression that I've got one super lazy male. Unfortunately at this stage it would be the best way to differentiate the parents from the rest. Maybe watch the female RTM and see if she behaves somewhat lightly or forgiving towards any of the other fish approaching the area. I've had situations where the male has been shooed off by the female because he started to eat the eggs, but then over time deceived the female into allowing him back into the area for him to feast on them.
Just remember that as long as the eggs are a brownish colour and aren't white, they're fertile and still alive.