I believe even a tiny amount of contaminant (which could have been ice) can be enough to help seed a blockage. A bit like how a crystal can form. Meteorologists sometimes prevent hail forming,and help moisture turn into heavy rain drops, by seeding the atmosphere with aluminium dust.
You might be able to clear a blockage by reverse flushing, maybe by disconnecting a pipe and alternately sucking and blowing air and fresh water. ., Try not to get any fluid in your mouth. It tastes horrible

(I should image

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