The "Recover seed" button in Sia-UI will sweep your funds from the seed you entered to the current wallet you are using in Sia-UI, thus all the funds from #1 was transferred/swept to wallet #2. Hence the 0SC you see in wallet #1 after you use the "recover seed" button. Using the same seed on 2 separate machine is not recommended as it can cause problems.
Make sure you are using the latest version of wallet (v1.3.1/v1.3.2).
Go to the terminal in Sia-UI and type consensus, make sure your blockheight is the same or higher tha n the blockheight shown here https://siastats.info
As long as the transaction can be seen on the blockchain, the transaction is completed and you do not need to worry.
(I recommend you to switch to Luxor to distribute the network hashrate since SiaMining now have more than 51% of the network hashrate)
I would advise you to stop mining Sia using GPU because ASICs or mining on the network now. You won't be able to compete with ASICs and your mining reward will be super super low. If you really want some Siacoins, you can mine other coins and convert them to SC.
Sia really does need to improve its host ledger reporting, and I'm not sure why no positive transactions ever show in the Wallet from contracts. Right now, when my contracts finish, I do notice my wallet balance does increase (assuming I don't have new contracts that simultaneous decrease the balance), and when running host -v I see numbers go up within the Host Financials sections. But I don't know a way yet to VERIFY that these numbers are correct, to correlate exact amounts with specific contracts, etc.