Uploading files not working after upgrade from 4.x to 6.x and mongo from 4.0 to 5.0

What version are you coming from? 4.8.7

What version are you going to? 6.4.5

What deployment method did you use to deploy? Docker

Did you follow a particular doc? Which one? Docker guide

What issues are you running into upgrading? We cannot download or upload files to our Rocket instance after the upgrade, this is also sitting behind an NGNX reverse proxy. so far I’ve checked everywhere on a setting, but found nothing.

When I try to upload a file to any channel or 1:1, I get the Select file dialog from my OS, then the Rocket confirmation to upload, but the file is never actually posted on the channel.

If I go to the Files button on a channel, I see all previously uploaded files, and when I go to the 3 dots and select download, nothing happens.

Anybody has a clue on which log or place I can look for the error and hopefully fix it?
Thank you!