I'm not sure if i'm staking to be honest, the staking amount has remained zero throughout although i have it enabled
I re-started the wallet last night a few times. It didn't seem to do anything at the time but then it started to show up. I've only caught a small handful of blocks between the two wallets in that time. Maybe 5? And there were 4 stale ones (showing in the history tab but no confirmations).
Also, I think when the spendable goes down, that must mean that the amount going to staking returns "principal and interest" so to speak, where principal is the number of coins used for earning that particular interest payment? I had a good chunk of old coins, perhaps those are given a very hefty weight in the very early blocks. Once the 510 blocks catch up, the 8 hours will be met and they will have a normal weight. Your coins are relatively newer than mine, I expect when you do catch a block, it will be a nice reward.
I'll be telling all my friends who bought theirs last year to update their wallets and start staking, for sure.
Does your wallet say "Staking" with a little circle at the bottom?
And with that, I will go take my seat, maybe get some popcorn. 
