I believe Lady Russell somewhat suffers from a delusion carried by many adult friends of young people. For most of their friendship, Anne has been young and probably relied upon Lady Russell for advice and guidance as any reasonable young person might.

But Anne is no longer a child. She knows who she is and what she wants. She needs no conformation of her instinctual and supported view that Mr. Elliot is not to her liking. She is not to be persuaded this time by Lady Russell and she never was persuaded that Lady Russell's distaste for FW's personal traits was merited.

I don't think Lady Russell wants to force Anne to do something like marry without any attachment. What she probably believes is that Anne is being silly about Mr. Elliot.

I am sure Lady Russell thinks Anne still carries feelings for FW and perhaps that this is the reason. Afterall, FW and WWE are very different. FW is to Anne's taste. WWE is to LR's.