Certainly sounds like the bug again, but to be certain, it might be worth raising a ticket - hopefully CS can at the very least check the logs on their end and see if the items have been removed by guild members or not.
The only problem is, because there has been such a major bug fairly recently where guild vaults got emptied, CS have had lots of tickets regarding that and I’m pretty sure by now they don’t actually read tickets relating to the guild vault, but give them the standard “nothing we can do” response. So you might have to persist a little in order to get someone to actually read your ticket in isolation.