I hit a wierd bug that crashes a built and packaged game when a UMG widget scripts hits a “play animation” node to sweep a box. Diden’t matter what I did, it would always crash if the “play animation” node was used. I had to copy/paste everything into a new widget blueprint and now it works as normal.
Possibly related to the other UMG/Widget issues in 4.17 when upgrading from 4.16(or other):