@elias.munoz.neyra I have experienced this quite a number of times now where keyboard shortcuts immediately stopped working. Restarting Revit seems to be the only solution. You said that "In order to determine the cause the problem needs to be repeatable" well I hope this will help in find a more reliable solution. When ever I do a match property and accidentally press "msa" instead of just "ma" the keyboard shortcut stops working.