An awful bug has been reported by Pain in this discussion.

It only concern challenge mode players who play in team :

If players A and B are playing together in challenge mode, their inventory and others data are saved in the set "Challenge mode game, Team: A B"

If the game was hosted by A and the player B quit the game, the solo dataset of player A is overwritten

It's a very bad bug, I think I can correct it on the worldserver side, and will look at it this evening and tomorrow's evening, you will be informed.

Until I correct it, if you want to preserve your solo progression, try to not host a multiplayer challenge game with teammates

The same problem happen if players A, B and C are playing together, if C quit the game, the data set "A B" is overwritten.

Excuse me for the convenience, and thanks to Pain for reporting the bug.

Thank you, Pat!

I'm glad that this incident has helped in uncovering a serious bug. It sure left me without my solo challenge progression, but at least it will prevent such things from happening in the future. Besides, it didn't turn out to be a major inconvenience as I had already managed to claim my star. Your response to this issue is as fast as ever (judging from the history of this forum).

This seemingly modestly active game is actually up and running, all thanks to your efforts! Keep up the great work!

This bug is harder to fix than expected, I probably won't beat it until the week-end.

Sorry for the convenience.

I've corrected the bug from the WorldServer side, you have nothing to download. Challenge mode teams should not encounter problems now.

I have also enhanced the player page, now inventory sets are sorted from the last used to the older.

Thanks again. I knew you could do this!