I provided exhaustive analyses of the chronologies and witnesses's account associated with the engagements of Paul Whiteman in Cleveland in Nov 1928 and Jan 1929. Here are some links
The only two firmly documented facts are that Bix had a breakdown in Cleveland on Nov 30, 1928 (Tram's diary) and that he was not present (Cleveland Press) at the Whiteman concert in Cleveland on Jan 20, 1929. The rest are recollections from musicians, conjecture, educated guesses, and speculation. The above links provide a detailed evaluation of all witnesses's and biographers's accounts of the events in Cleveland in Dec 1928 and Jan 1929.
The third documented fact is that Ray Miller recorded "Cradle of Love" in Chicago on Jan 24, 1929.
My summary in one of my postings was as follows,
It is possible that Bix went to Cleveland with Whiteman on Jan 20, 1929, that he had a breakdown in his hotel room, that he was sent to Davenport, that on the way to Davenport [on Jan 23] he stopped in Chicago, got in touch with Spanier, went into the Brusnwick recording studio [on Jan 24] with Miller and his boys, and that he recorded the solos in "Cradle of Love." It is just as possible that Bix went to Davenport from Cincinnati, did not have to wait four hours for a train to Davenport, continued on home, never got in touch with Spanier, did not go to the Brusnwick studios with Ray Miller and his band, and did not record "Cradle of Love." Both scenarios are hypothetical, speculative. If the aural evidence convinces you that Bix is the mystery soloist, then you accept the first scenario. If you don't hear Bix in the mystery cornetist solos, then you favor the second scenario or any other plausible account of Bix's chronology between Jan 10 and Feb 5, 1929. The firmly established chronological facts do not favor one scenario over [any] others.
My proposed scenario was provided in another posting.
It seems more likely [note that I was not giving my interpretation as the gospel truth; I point out the phrase "more likely"] that Bix went along with Whiteman and the boys to Cincinnati on Jan 12, 1929 with the idea that he would continue on to Davenport for recuperation. [He had been in a hospital with pneumonia in Dec 1928 and perhaps early Jan 1929]. That is my interpretation, speculative, [again, no dogmatic assertion, I qualify my version as speculative] of course. There was a special Whiteman train that went directly from New York to Cincinnati, [on Jan 12, 1929] and it makes sense that Bix would take advantage of the facilities. Thus, Bix, in my scenario, perhaps after a day or two (or more) of rest in Cincinnati left for Davenport. I propose that Bix spent the remaining of Jan and all of February at home. He did not join Miller in Chicago for the recording of "Cradle of Love" on Jan 24, 1929. By Feb 5, Bix was well enough that he wrote to Tommy Rockwell and a a couple of days later was interviewed by the Davenport Sunday Democrat.