IBus input not working in QT applications

I'm using Ubuntu 21.04. IBus Chinese (ibus-libzhuyin and ibus-libpinyin) works in all gnome applications but it doesn't work for any Qt applications like Anki.

I've tried adding this in ~/.xprofile (I read somewhere to do that):

export XMODIFIERS=@im=ibus
export GTK_IM_MODULE=ibus
export QT_IM_MODULE=ibus

But doing this seems to have no effect.

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