There seems to be some sort of bug related to accounts (which I know you intend to deprecate at some point, but still exist). Bitcointalk.org uses the used-to-be-standard accounts pattern of getaccountaddress <account> & getbalance <account>. Upon upgrading from to 0.16.0, it seems that about 10% of addresses given out by getaccountaddress X later do not have their account assignment anymore. They aren't reflected in the getbalance X balance, and the account does not show up in validateaddress.
I haven't tracked down exactly where the account assignment gets lost. Maybe it's sometimes never made, or maybe it's lost after a while. In some cases, getaccountaddress might've been called twice in quick succession on the same account, so maybe there's a concurrency issue.
I'm just going to take this opportunity to get rid of accounts usage. Though I suppose that other people will run into this problem, since it was the standard pattern which everyone recommended using from about 2011 to 2015.
