These are the photos of the crank gear & the two thin plates that goes at front and back of it, from late 2015 when I did my timing belt kit. Basically the plates+crank gear should snugly fit onto to the crankshaft end in front of the seal when the harmonic balancer is inserted and tightened with the pulley bolt.
https://photos.app.goo.gl/CKOqHLOjIIpkA6P62
https://photos.app.goo.gl/Ni83tMzrAniqAwdl1
https://photos.app.goo.gl/bCOaF1Bb0DnOR08S2
So, you can see there is a slight protrusion out of the crank shaft for back plate+crank gear to touch, so they don't grind on the crankshaft oil seal. I'm guessing the reasons for your drama might be a loose harmonic balancer bolt or the crankshaft key wear or something along those lines???!!!