This usually occurs after adding multiple folders from separate mega links.

Lets say I want to add three folders which have 100 files each. Only the first folder will appear in the transfer manager.

Only once the first folder is finished will the second folder appear in the transfer manager, and this repeats for each folder.

This is a problem because upon closing the mega sync app and resuming it, only the currently active files in the transfer manager are remembered. This means that the first folder which was in progress before the application was closed will be resumed, but the second and third folders will not be downloaded at all.