I suspect you've left the 'ventilation covers' off the crownboard so that the bees have access to the roof space.
Try gently sliding a hive tool between the roof and the super and prising it slightly. Try on a hot day when the propolis is warm. Perhaps even better try with something wider than a hive tool so the pressure is spread over a wider area. Repeat on as many sides of the roof as you can access.

In my experience the roofs are a bit fragile ... I've had a couple blow off and get damaged. Deep they may be, but once they take flight they are light and travel a long way ... and land with a crash