I think it might be that it's missing a large part of the lower frequencies, not that entire bass sound is missing. And I guess it'd be hard to faith-fully regenerate those, if we simply don't have a lot of samples.
Source: have degree and postgrad in jazz and used to be a bass player. Have made transcriptions of early bass players from original recordings. (by ear without any kind of fancy tech)
[1] and the playing technique for various reasons.
The Mooche
* https://www.youtube.com/watch?v=BPJ5vNmVL3I (The Duke, 1928)
* https://www.youtube.com/watch?v=tLdCq2PKM4o (John Barry, 1984)
Sugar Foot Stomp
* https://www.youtube.com/watch?v=qEdIWVsfPXs (Henderson, 1925)
* https://www.youtube.com/watch?v=35foefTrdLo (Nighthawks, 1993)
Doctor Jazz
* https://www.youtube.com/watch?v=HTYAaX7lqjQ (Morton, 1926)
* https://www.shazam.com/song/1687138286/doctor-jazz (Asaro & Fat Babies, 2016)
I was wondering if anyone was working on this (i.e., using pure software). Period equipment, real musicians, and such would be time consuming, arduous, and cost prohibitive.