You had it set to change the background colour only, and the new colour for background was set to black. So it was colouring properly, only on a black background the colour change couldn't be seen. The problem is fixed by setting the trigger to colour "Both":
I have this trigger to make any line that starts with an asterisk stand out bright yellow. For some reason I can't figure out, it won't colour the lines, but it does match on them properly, and if I put stuff in the send field it send it.
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