Emails messages show on Usermin but does not show on RoundCube

Hello all,

I have one customer email account with lots o folders. All the folders have messages on them. When I access the folders using Usermin, I can see all the messages in all folders. But when I access this same account using RoundCube some folders come empty, with no messages. I can see all the folders, but when I click on some of them no messages are shown. Other folders show the messages correctly.
What can be the cause of this? And how can I fix it?

Thank you