I've already the same problem, sometimes when I download a new windows QT, there is no transactions appears in the list!
but when I dump the wallet, that show me a list of transactions that they had mined since 2015! (in the txt file)
Dumping the wallet does dump the private keys of your wallet. There shouldn't be any transactions visible in the dumped file.
Is there any tips to recovery my transactions?
Are you trying to recover your BTC's (which seem to be missing in your eyes) ?
Or are you trying to recover the transactions inside your wallet (so that they show up in a list) ?
Do what buwaytress said, check the balance of your transactions in a block explorer (e.g.
Blockcypher or
blockchain.info).
Usually you will see your balance and all transaction after core has synced.