In SMAPI 3.8.0, Cursor.Tile that comes from the event arguments returns the wrong tile if you change either zoom level or UI scale from 100%. This happens atleast in the ButtonPressed event.

Comment from #742 (which I presume is a duplicate, although on closer reading I'm not sure):

The value returned by IModHelper.Input.GetCursorPosition().Tile called from a non-UI context is incorrect when the zoom level and UI scaling are different. The value appears to be calculated using the UI scaling.

This is either a bug in the implementation (or possibly the API design is no longer sufficient if it returns the correct value in UI contexts), or a bug in the documentation (which should indicate that the value can't be used reliably in non-UI contexts if that's the intended behavior).

To Reproduce

The following code snippet is inside an OnUpdateTicked handler (with checks to only run every 6 events and only when the player has an item equipped, to keep it from blowing up my log too much).

    var cursorTile = helper.Input.GetCursorPosition().Tile;
    var mouse = Microsoft.Xna.Framework.Input.Mouse.GetState();
    monitor.Log("UiMode " + Game1.uiMode + " zoom " + Game1.options.zoomLevel
        + " uiScale " + Game1.options.uiScale
        + "  " + cursorTile
        + " | " + (int)((Game1.viewport.X + mouse.X / Game1.options.zoomLevel) / Game1.tileSize)
        + ", " + (int)((Game1.viewport.Y + mouse.Y / Game1.options.zoomLevel) / Game1.tileSize)
        , LogLevel.Debug);
    monitor.Log("  mouse " + mouse.X + ", " + mouse.Y
        + "; viewport " + Game1.viewport
        + " uiviewport " + Game1.uiViewport
        + " baseZoom " + Game1.options.baseZoomLevel
        + " tileSize " + Game1.tileSize
        , LogLevel.Debug);

Here are a couple of lines from the output before and after I changed the UI scale (with the cursor over the same tile):

 UiMode False zoom 0.75 uiScale 0.75  {X:68 Y:23} | 68, 23
   mouse 733, 371; viewport [3413, 1019] - 1707 x 960 uiviewport [3413, 1019] - 1707 x 960 baseZoom 0.75 tileSize 64

 UiMode False zoom 0.75 uiScale 1  {X:64 Y:21} | 68, 23
   mouse 719, 360; viewport [3413, 1019] - 1707 x 960 uiviewport [3413, 1019] - 1281 x 720 baseZoom 0.75 tileSize 64

The coordinates on the first line of each output are different, and they should not be.
Obviously I did find the correct way to compute the tile myself, so I'm in no hurry for a fix, but I assume there are other mod developers who will trip over the same thing.

This seems to be related to the commit 85cb824

Replacing Game1.viewport with Game1.uiViewport in src/SMAPI/Framework/Input/SInputState.cs:209 looks to be the culprit at a quick glance since the world tiles aren't dependent on the UI scaling.

Edit: Disregard this, I had a chance to get into the game, and it seems I might not be on the proper track. I'm leaning more towards a zoom ration of UI:World zoom level.

Fixed in develop for the upcoming SMAPI 3.8.2.