Not sure if it is related to my recent replacement of my 2016 MacBook Pro with a 2018 MacBook Pro, but about a week and a half ago, I started having issues with hotkeys shuffling around spontaneously. I logged onto my main character in windows and none of the hotbar abilities worked (1 2 3 4 5), weapon swap, and mail. I was able to get the abilities working by dragging the abilities back to the bars, but weapon swap was still not working.
I went into settings->controls, and saw that for some reason weapon swap was now assigned to '\'. I switched it back to '`', and was good to go, til I tried logging into the mac client, and now weapon swap had to be reassigned back to '`' again. So now whenever I switch clients I have to reassign weapon swap to '`' and mail to '''.