We created a board with many images on it.

In a workshop, where 60+ people joint the board, those 60+ people all couldn´t see the uploaded images whilest the 3 people who prepared the board still could see the images.

After a while some of those 60+ people refreshed their page and after that could see the uploaded images.

What’s the reason behind this issue and how can we solve this for our upcoming workhsop with the same board design and more than 70 people on it?