I have a soft low spot in the floor , about the size of a dinner plate. just about center slide area near end of sofa. '02 U320. just looking for others insights before I start removing Vinyl plank type flooring?
Don't think anyone can give you a solution or a insight except start taking up your flooring and be prepared for some damage,
soft spot probably means it got wet and you have rotted wood,all we can do is tell you what it might be and help you with a solution when you find out what exactly is going on.Maybe use a oscillating tool to cut the top layer of flooring to see below,you
could always put that cut out part back temporarily after the repair.