Can't export local world to realm

Hello,

My friends and I recently have purchased the Nintendo Switch's Minecraft version. In order to play it whenever we want from anywhere we were, even if we were separated, I purchased a two friends realm suscription. We had already started playing in local, so I wanted to export our world to the realm I purchased. At first it worked okey, but some time later we needed to export another world, and it did not work. I have been trying to export it for the last week, but nothing changed.

It starts exporting but lasts a second until an error message appears. I would like this problem to get solved, I still have a lot of days of realm suscription, not counting with the ones we have already lost.
Thanks for your time and your atention,

Greetings, Iñaki