There is one test that will tell you which device is wrong, it costs nothing, and it takes about two minutes. Do this before you buy any hardware.
USE A SINGLE-WORD PASSPHRASE. No spaces at all. Something like `correcthorse`. Enter it on the Coldcard and on a Jade and compare fingerprints.
You already know two data points:
no passphrase -> fingerprints MATCH (so the seed is identical, confirmed)
multi-word passphrase -> fingerprints DIFFER
The single-word case splits the remaining possibilities cleanly:
If the single word MATCHES, the problem is entirely in how one device handles the SEPARATORS. Something is trimming, collapsing, or adding whitespace between your words. That is your answer, and the fix is to stop using spaces — a single long passphrase with no separators sidesteps it completely and loses you nothing in entropy.
If the single word STILL DIFFERS, it is not whitespace and something more fundamental is wrong in the passphrase path on one device. That is a much more serious finding and worth reporting to whichever vendor turns out to be the odd one.
Either way you stop guessing, which is where you are now.
HOW TO TELL WHICH DEVICE IS THE ODD ONE OUT
You have three Jades agreeing and one Coldcard disagreeing. That is suggestive but not proof — agreement among three units of the same firmware is one implementation, not three independent ones. They can all be consistently wrong together.
BIP-39 is unambiguous about the correct answer:
PBKDF2-HMAC-SHA512( password = mnemonic in UTF-8 NFKD,
salt = "mnemonic" + passphrase in UTF-8 NFKD,
2048 iterations, 64-byte output )
The salt is the literal string "mnemonic" concatenated with your passphrase exactly as given. No trimming, no collapsing of spaces, no case changes. Any device doing anything else is deviating from the spec regardless of how many of its siblings agree with it.
ON THE HARDWARE DIVERSITY PROBLEM, and a trap to avoid
Do not solve this with Electrum on the Pi without checking one thing first: Electrum does NOT generate BIP-39 seeds, it uses its own format. For a multisig with BIP-39 devices that matters. It CAN import an existing BIP-39 seed and sign PSBTs fine, so an airgapped Pi running Electrum works as a third signer — but only as an importer, never as the thing that generates the seed. Generate elsewhere, import there.
For a cheap third device with a screen, Krux runs on M5StickV-class hardware and SeedSigner on a Pi Zero with a small display — both land around thirty to forty of whatever currency you use, both are airgapped-by-design and camera-based. That gets you genuine implementation diversity rather than a third unit of something you already have.
BUT DO THE PASSPHRASE TEST FIRST. If it turns out one device mishandles separators, buying a third device does not fix it — you would just have three devices and the same unresolvable fingerprint, and you would have spent money to stay stuck.
And whatever you conclude: do not fund a multisig whose fingerprint you cannot reproduce on demand. You already worked that out, which is why you are asking rather than sending. That instinct is the correct one and it is worth more than the hardware.
