Thunderbird autocomplete

Thunderbird used to be very smart about autocompleting email addresses for me, suggesting ones that I had emailed most recently or most frequently. But a month or two ago, the behavior changed. Now it just suggests the first one that comes up in strict alphabetic order, which is almost never the one I want. I assume there must have been an update that changed the behavior, but I can't find an option to toggle. I want my smart autofill back! Any suggestions?