Like other posters, Sim Update 5 (126.96.36.199) has broken the MSFS mouse support on my up-to-date Windows/Nvidia PC, empty Community folder.
I think it’s unhelpful closing the thread so quickly as ‘solved’ when other people are going to hit the same issue and it might not be (hence this new thread).
the mouse moves around as normal, blue highlights appear on clickable in-cockpit objects, clicking or dragging the mouse has no effect.
If it’s a clue, if I hover the mouse over the throttle in the Cessna 152, the tooltip says “Hold [?] to lock”.
It seems possible the mouse profile is broken, I’m pretty sure it used to say “Default Profile” but now it says “Mouse Profile”, but if I change the Mouse option to “Default Profile” MSFS crashes to desktop.
For other readers the ‘Legacy’ mode for the mouse is under “General Options” - “Accessibility” - “User Interface” - “Cockpit Interaction System”
If I change the “Cockpit Interaction System” to “Legacy” it IS possible to interact with the cockpit elements as before (with new icons/tooltips), but still if I try and change the mouse profile to “Default” a CTD occurs. So after a couple of hours I have managed to get a working plane but I would not consider this ‘solved’.
Possibly another clue is the in-flight pop up menu (the one with ‘Weather’ etc on it that appears when you move the mouse near the top of the screen when flying) has a ‘yoke’ icon labelled ‘Basic Controls’ which has a new (!) on it but on clicking it a translucent page labelled “BASIC CONTROLS” appears but apart from a couple of empty select boxes near the top this page is blank.