It only happens on the first load of a save game after i started Skyrim.
When i already have a two handed weapon or bow equipped on loading the save.
Then when i try to switch to a one handed weapon from the normal inventory using right mouse key (put to off hand) then the game will not switch to the weapon and when i close my inventory soulsyui will also still show my old weapon equipped. If i repeatedly try to click right mouse on my one handed weapon in the inventory that i want to equip the game will either crash or freeze up indefinitely.
I can get around this bug by unequipping both hands first after i loaded the game. After that switching from bow to one handed (using right mouse) from the inventory works fine. Reloading a savegame does not trigger the bug again until i relaunch Skyrim. Using left click to equip always works fine.
I tested it on 0.16.2, 0.15.1 and 0.14.1, happens on all of them. I tested this also without sously enabled and right click from inventory works.
I hope that helps and you can reproduce the bug. I think it has something to do with me using right mouse instead of the usual left.
Novablue1987 on nexusmods reports this: