That is very odd. I am not sure what to suggest next. Is it possible that all of the views on the active sheet of the active drawing are at 'custom' orientations, rather than standard orientations? It is possible to set a view to a custom orientation, so that it is not perfectly aligned with the origin planes of the model and not in a perfect ISO view orientation either. And if the 'base' view on the sheet was oriented that way, then all the other views on the sheet were oriented based on that base view's orientation, then in theory it may be possible for all the views on the sheet to be a little 'off'. I have seen this myself before too, in rare occasions years ago, where we created models in 3D space, then reoriented the 'view cube' to be based on some aspects of the model, instead of aligned perfectly with the origin planes. And in some cases that was somehow done by mistake, so we did not notice until we encountered the problems with the drawing views later, because the model face used for orientation was nearly parallel with an origin plane, but not exactly. I don't know if that is the case here, but may be worth looking into.
The screen captured image below was taken while in Edit Mode of an ISO view on a drawing, and while in that mode, you will usually see the view cube shown somewhere near the view, which allows you to manually change the orientation of the model view. While that view cube is showing, if you click on the little down arrow near its bottom right corner, there are two special options available for how to set the orientation of the view. The one named "Custom View Orientation..." will allow you to view the model in model space briefly, allowing you the opportunity to orient the view manually to a non standard orientation. The option named "Current Model Orientation" will capture the current view orientation that the open model document was at before switching to (or activating) the drawing. While using the 'custom' route, you can use the 'look at' tool to straighten the view so that it is looking directly at a flat face or plane. Some folks use that to get a better view of odd shaped designs that may look better from an off angle.

Wesley Crihfield

(Not an Autodesk Employee)