We've had an Eglu cube plus a large walk in Omlet run for a few years now and never had any problems with unwanted visitors.
All food is stored in our garage.
This winter we have noticed tunnel holes from outside the run, under the fox lip and then into the run. It started with one hole, but now there are about 10 all around the run and we have spotted a rat out there. Has anyone got any tips of how I can adapt the run to stop them?