Apparently Burton got in due to AAA campaign of no transfers to SF.
That's completely crazy given that there were no AAA transfers to anyone. Ruth Coppinger took the second seat but didn't reach the quota. Every AAA vote was used up on the AAA candidate. Even if every single AAA voter had Donnelly number 2, he would have got zero transfers. It's also completely crazy in the sense that the AAA said nothing at all about transfers to anyone anyway.
Coming on here with your pesky fact after 8den has already pronounced what happened...
Donnelly lost to Burton because his campaign was complacent and didn't get all of their vote out. There was a widely publicised constituency poll during the campaign, which showed Coppinger edging out Burton for the last seat with Donnelly romping home. The bookies had him 100/1 on to take a seat. The poll had the effect of galvanising support for Coppinger and Burton, with it looking like a straight choice between the two. Meanwhile it looked like SF had a seat in the bag and it was taken for granted. The Donnelly camp are now extremely sulky but they only have themselves to blame.
No doubt there will be questions in the Kremlin over this. SF pride themselves on their vote management.