Unfortunately I can't find the voting advice list but I'm 100% sure they preferred Labour over the SNP although initially they stated they didn't. After criticism they said it was their choice. Also an anomaly in 2019: pro libdem in unwinnable seats + anti Labour under Corbyn: conclusion???
The link I see between 2019 + 2024 is that BfB probably wasn't that open about their goals. 2019: probably trying to get rid of Corbyn. 2024: GTTO ( Starmer in) & undermine the SNP at the same time.
I did a bit of research. They used Survation to carry out their polling and create the MRP, so it should be as good as any, after all they are a professional polling company. The whole point about using this method is that it accounts for local differences. The polling advice I got from them was
… to vote SNP & this was the same across other tactical voting sites. You obviously had something different. But the general picture then was that the SNP would lose seats and so they did. One of the things I know about Alex Andreou is that he voted for Corbyn in 2015. I also doubt that BfB is…
… interested in the SNP or Scotland in general. London politics loves London. The SNP had bad spell and that was reflected in their support.