Monero "looks ahead" 200 subaddress indices from the highest subaddress index that it observes it has received an incoming payment to.
Therefore if you ever issue more than 200 subaddresses in a row and none of those receive any funds to them, then you need to force your wallet to scan beyond the subaddress index that it would normally stop looking beyond.
To do this, use the command line Monero wallet (CLI) and type address new as many times as necessary to get the wallet to recognize higher subaddress indices. Then type rescan_bc to rescan the blockchain for those higher numbered subaddresses.
I also want to know if I can get all 60,000 subaddresses from a just
recovering key from a mnemonic seed
Yes, you can use the --subaddress-lookahead option when restoring a wallet from seed using the Monero CLI (command line interface) wallet. E.g. use the command ./monero-wallet-cli --restore-deterministic-wallet --subaddress-lookahead 50:70000 to automatically scan the first 70,000 subaddresses for each wallet in each of the first 50 accounts. Note that unlike the GUI, the CLI allows multiple accounts each with multiple subaddresses. If you've only been using the GUI so far, then you'll only have one account.
