Locked off xyz / assembly misaligned

Object off on XYZ, when i tap cube to lock in object i can see that it is slightly off, if i lock on an axis, and i draw a circle……then when I view it from another axis point (side view) you can see that it is slightly off. I see how the assembly is off (something i did) but everything is off, even the circle drawn while locked. I would otherwise be able to lock in a plane and align objects to the plane……but the plane is off………my work around is to open another sketch and make a cube then import the cube into my drawing………but if i align the face to the cube it doesn’t fix the problem, and the cube is off, however if i align an objects edge to an edge on the cube the problem goes away………this happened once before (both times on large assemblies), and its easy enough to fix, but hard to see until it presents a problem aligning objects (they align fine, but visually their off)…….im just curious how i create or how the problem is created……………thanks

I would send a video of the problem but once i fixed it i forgot about it for several days, and could not go back……….and though i tried I can’t duplicate the problem…….thanks