You guys should see on the transactions page if the stake has confirmed or not. My guess is your coins staked a block and just haven't confirmed yet. It usually takes a couple (to a few) hours for them to be available.
Is that due to less number of people staking?
No. This is how staking works. When you stake a block, your coins move over to the stake column and are unavailable until the block is confirmed (just like how you don't get your coins from a mining pool until like...120 blocks later). If this is indeed the case (and not some weird wallet issue), then you'll see this on the transactions page.
My best guess is the update combined the inputs from people wallets and now there are not enough inputs/coins to keep the block chain moving. It has been on block 1944 for a while now.