This problem was so bad that I gave up using Band in a Box for composing songs and only used it as a rehearsing backup band with my guitars and midi keyboard. When I tried to record my keyboard to the melody track, I got no midi signal coming through, or it worked sporatically once in a while. This was going back to when I bought BIAB 2017.
The solution was to start from a new song file to which I added a melodist song, then recorded to the melody track from there. Now the process works correctly every time. So my problem was with my old song files, some of which dated back ten years or more that were re-saved through multiple versions of BIAB as I kept working on them. These files became corrupted or incompatible through newer versions of the program. I'm glad to be back starting songs in BIAB instead of starting from scratch in Studio One 4.

Thanks jhg!
Something to watch out for.
You may want to also post it in the "Post your own Tips and Tricks here" Forum.

Virtually all of my songs start as MIDI in BiaB prior to drag and dropping them in Studio One Pro. I am a firm believer of this workflow and I think you are making the right move.

I start in BiaB, save my BiaB file, and then export to the appropriate MIDI sequencer or DAW (depending on my need) to take the very good product BiaB produces and make it even better, add other parts, and make it the best my talent and tools allow.

Even after finishing on another app, I never delete my old BiaB file because I may want to use it again, or do something else to add to the Sequencer/DAW project.

Insights and incites by Notes