UE4 Freezes when I use foliage editor?

When drag a static mesh into the foliage editor, sometimes it brings up the “loading package” screen and it gets to 99% and then UE4 just stops doing anything, and never comes back, the only way to close it is through task manager.
Also, when I drag the static mesh, cpu usage jumps to around 95% for like 10 secs, then back down to 5% and the editor is frozen, while pc doesnt recognize it as a crash or not responsive.