How really are the maximum dimension of files we can upload

have tried to upload these files to a group several times (and then also tired uploading them to my (private) files. Whenever I tried, the encryption process runs well and then they appear in the folder where I wanted to upload them to, but:
- but after few minute they disappers from upload activity
i close wuala and open it thay appers on upload activity but they disappears again...