This is because all bending data is cleared when players logged out. Although it's bad in this case, this is so a player doesn't join for a second, leave again, then never return while the server still holds that data in memory. ProjectKorra especially uses a lot of memory so preferably, we want to try keep memory down as low as possible and this is one of those ways.
So as such, we might not be able to completely fix it but we may be able to create a workaround. No promises but we'll see what we can do.