Two questions.
1) Is there a soloist dialogue in RB I haven't found?
Not that I'm aware of; you just generate a new track in RB using a realtrack, Soloist is more of a BB term
2) Can I only generate a new RealTracks track successfully if I work on a sgu fle not a seq? If that's true then I need to get my RB tracks right before I save them to seq files which seems odd.
No, SEQ files should be able to generate new tracks freely, this is an odd behavior you describe, so getting a copy of the SEQ file would be nice. Have you checked out Dropbox as an upload option? It usually will allow a SEQ size file.. and has free options.
Wish I could help more, but what you describe has been done regularly for years here. Something seems amiss with how you're setup or how you are trying it..