Hi @javier
Which version of Metabase?
Do you see any warnings/errors in the log? Check either Settings > Admin > Troubleshooting, or the log file, which should be located in ~/Library/Application Support/Metabase/
But there’s not a lot of solutions - these are open issues. Two of the issues has milestone 0.33, but I’m not sure if they will be fixed by that version.
Since someone commented on issue #9428 that it happens on some of their MongoDB tables, I would suggest that you click the Subscribe-button on the issue to get notified when anything happens. And click the to upvote issues.