Hi, I have strange issue so I need help to solve situation.

I use ubuntu 18.04., 8 cores 24GB RAM.

I had old node (v0.16.3) with wallet version 159900, and about 100 accounts/addresses in wallet.dat file and I have daily backups of wallet.dat.  I also deployed new node (v17.1) and fully synced, then stopped old node, transferred wallet.dat to new node and started new node. It started fine, everything is working as it should because I did this many times before with both btc and other coins.
But everything was not fine. First symptom is that bitcoind with copied wallet.dat is causing high CPU usage (100%) , bitcoin-cli commands are very slow to return balance or list of accounts, and after a while (5-15 minutes) it will crash. Then I reverted to old same version (v0.16.3) and recopied original wallet.dat. Same issue again. With newly created wallet (empty) it is working fine, so there is definitevely some issue with old wallet file itself. I also tried various options as full resync and salvagewallet, but issue persisted. I also opted for another approach, I dumped private keys from original wallet, and imported into fresh new wallet and did resync. Now, I have full balance, ntc is working normaly (low cpu usage and no crashes), but now all balance is on default account ("") and not in separate accounts / addresses as it was originaly. I have option to manualy transfer proper values to each account (with move) but this is last resort option. I would like to get opinion or possible solution for this issue. Db.log do not show any errors or warnings when starting or while working, but clearly bitcoind has issue with my original wallet.dat file. As I mentioned I was using this process many time before (copying to other node or restoring from backup) with zero issues but this time it is hard to catch the cause of problem and to find solution.

Thanks in advance.