xtitle -s -t 30 runs fine in a terminal, but in i3blocks it will eventually just freeze in some window title and not update itself any longer, requiring i3 to be restarted.

Another one is having the same issue: https://www.reddit.com/r/i3wm/comments/fsf26n/xtitle_in_i3blocks_hangs_in_bar/

My config:
[title]
command=xtitle -s -t 30
interval=persist