Yes there is a race condition. I saw some items being updated from Undef to OFF triggering some rules in doing so, so it’s not being done in order as it should. I also have a similar amount of items.
Reminder; new-born Items start life with state NULL. If you are seeing state UNDEF, a binding has done that. (I’m assuming you’d have no rules that do that).
I think restoreOnStartup is smart enough not to restore Items that are not NULL, so it shouldn’t even be in play in the case described.
I double-checked and they were NULL and not UNDEF, sorry about that.