For reference, we already discussed this on the subreddit:
One important piece of information to take away here is that you did not
just create a new i3 config, but you deleted your entire home directory,
which removes all caches and configs of all other applications as well.
Post by Wilko Bartels
hey there. i did install i3 for the first time 3 days ago. at first
try i noticed if i assign mplayer,vlc or mpv(doesnt matter which) to a
specific workspace; lets say workspaces 6, and i start a videofile on
ws 1 for example the player starts on ws 6 and all is fine.
for a different reason i started all over again with a new config.
only to find out that the behaviour now is: player starts on workspace
6 and stops playback after a millisecond and only continues if i
switch to that ws; why is that? how do i get the other setting back? i
assigned the players now with the focus option BUT that was not needed
before and it started the playback in the background without the need
to switch there.