In the PG, the width of the sprite texture is 450px whereas the cell width is 112px => 450/112~4.01 > 4, so the system thinks there are 5 sprites in each row. As you only have 4 sprites per row, you should set a width of 112.5 (=450/4). Same thing for the height.
Setting noMipmap by hand does work for me (see the PG above), but it’s a bug that this property is not serialized. This PR will fix it:
And in my testing, setting the Clamp U / V properties on the texture (using the inspector) does change the wrapU/wrapV properties in the exported json. Could you retest on your end?