Logic Pro: Software Instruments Transposition

I chose the Marimba & Concert Grand Software Instruments. I've tried it with other sounds from the same batch (yes, they're all default Apple sounds, freshly downloaded) & every one of them is exactly one tone flat. I've looked at all the transposition settings I can find for Regions, Tracks, Instruments… I've checked the score for transposed pitches… I can't find any reason for it. (I've been using Logic since the dawn of time!)

I have no external devices apart from a keyboard, & it's not that because it only supplies notes & velocities — besides which, the same keyboard produces different pitches from the same note depending on which software instrument is selected. I have no pitch-related plug-ins.

On investigation, the Legacy instruments are all one tone higher in pitch than the current samples, which are the ones supplied by Apple for download with current versions of Logic Pro. Nothing is 3rd-party or out of the ordinary.

Don't worry — I've spent a lot of time looking into this! I was hoping for a simple explanation as to why Legacy & current samples should be one tone apart in pitch… but I can't find anything about this in the documentation. The obvious workaround is to MIDI transpose all the affected software instruments, but that CAN'T be the right way of doing things!

To reassure you about Regions: if you have two Tracks, one set to a Legacy Software Instrument & the other to a current Software Instrument, then simply dragging a Region from one track to the other results in a change in pitch (one tone either way). In fact, you don't need to have recorded any Regions; simply playing the same notes on the different Tracks results in different pitches being sounded.

Alright. I deleted the entire library of sounds & downloaded them again overnight. Everything is now fine. But… WHY? #GreatMysteriesOfOurTime