I agree that it is disheartening to see absence of activity on the Infinity Tower (or St. Bernard Place for that matter).
Aside from the Franklin Yards, things actually seem quite quiet downtown right now. Even the Gateway Towers seem to be at a near stall at present (I ascribe this to the finishing off of the Third Sister next door).
I don't know what the reason is for the absence of activity, and presume it is multifactorial. If there is no action by the fall, I will be truly alarmed........