DigiDollar mint silently fails with legacy BDB/non-descriptor wallet #443

The affected legacy wallet, JP_2025, was created in 2025 and was originally used with DigiByte Core 8.22.2. It was subsequently opened under v9.26.5. DigiDollar minting consistently failed with this BDB/non-descriptor wallet, whereas a newly created SQLite/descriptor wallet under v9.26.5 successfully minted DigiDollar on the first attempt.

Environment:

• macOS
• DigiByte Core v9.26.5 DigiDollar
• Mainnet
• Wallet fully synchronized
• Oracle active and not stale

Legacy wallet:

• format: "bdb"
• descriptors: false
• private_keys_enabled: true

When attempting to mint DigiDollar, the GUI correctly displays the required collateral and asks for the wallet password. After entering the correct password, nothing happens:

• No error message
• No mint transaction
• No DigiDollar vault
• No DD balance change

This was reproduced several times. Moving the DGB out of the wallet and back again to create fresh UTXOs did not solve the problem.

New wallet:

• format: "sqlite"
• descriptors: true
• private_keys_enabled: true

After transferring DGB to the new wallet, I performed the same mint operation:

• 100 DD
• 30-day lock
• 500% collateral
• 101,773.47843611 DGB collateral

The mint transaction was created successfully on the first attempt and the DigiDollar vault appeared correctly in the GUI.

Expected behavior:
Legacy wallets should either be able to mint DigiDollar, or the GUI should explicitly report that the wallet format is unsupported instead of failing silently.

I can provide additional non-sensitive RPC output or logs if required.