Why have I lost all my saved-up lives since installing the latest update?

Don't store the lives - they are meant to be used or they turn into beans.If you have 5 lives at the start of a game of Farm Heroes Saga, all additional lives that have been sent to you by friends automatically turn into beans. If you have less than 5 lives at the start of the game you will be able to receive lives from your friends and these can be stored until you close the game down. 

Just ask your friends for more lives if you should need them :-)

That's wrong and not fair, i've been stuck on a level for 2 weeks and i needed those lives to help me, how dare they just take them away!!!!

Hey Lesley, at least you get magic beans for them, which come in handy on the Rancid levels! By the way, I believe lives and other messages on Facebook are only valid during one Facebook session; so be careful when logging out because these may not be saved on Facebook!