I just had ArcGIS Pro upgraded to the most recent 3.3.0 after running into several errors with 3.2.1. But I have run into a new problem with 3.3.0: in the project I most commonly use, any attempt to turn a layer on or off causes Pro's interface to mostly grey out and become unresponsive. The cursor also gets the spinning circle whenever the mouse is anywhere except the map window.
The truly strange part of this is that the map window continues to operate semi-normally - it can be zoomed in and out and panned (if that tool was selected before attempting the turn on/off), although most right-click functions are also greyed out. Even stranger is that the layer I attempted to switch on/off does so successfully right as the interface stops working!
The close button in the upper right of the interface is also greyed out and unusable, although the minimize and restore buttons operate as usual. My only option to get out of the situation is a CTRL-ALT-DEL. When I do that, ArcGIS Pro does not show as being unresponsive.
I attempted to run the Diagnostic Monitor while trying to turn a layer off, and noticed a single task that never seems to finish running - ArcGIS.Desktop.Internal.Mapping.Operations.UpdateMapMember.Operation.DoAsync:

Has anyone run into a problem like this, or have any ideas for resolving it? I would greatly appreciate any help anyone could provide. Thanks!!