I have spent the last 9 months getting my solo chops together, not just physical/speed stuff, but melodic/harmonic ideas, phrasing. I think I have made some good progress. Now I don't get to solo much backing up a singer songwriter or playing covers in bars, but once in a while some vocalist will say: "Lets hear a bass solo." What follows is, I can't pull off any of the melodic phrasing that sounds so good at home, and I end up playing some meandering modal run, only to bail myself out by playing some funky groove to get out at the end. Am I practicing incorrectly? Is it a mental thing? Am I just so caught off guard that I'm being asked to solo in a Rolling Stones song, that I can't access that stuff?