Hi. Think of Solve's non-evaluation problem as something similar to what you get with Hold in Mathematica or with 'x' in Maple. I do not know if it is a change in the behavior of the plugin that is here to stay, or an unwanted effect due to an update, but what you can do is not define with := and ask in the same line for the symbolic result, but first define L := Solve (...) and then symbolically evaluate L ->
this means, SMath needs another step to proceed to evaluate the expression in Solve.