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I'm a bit confused too, but I'm guessing it's actually an IB operated BA codeshare, since that's an established route for that service. In which case definitely no compensation, the regulations specifically include strikes as grounds to deny compensation (
page 2, preamble point 14). If it was a BA operated flight that somehow caught up in IB's strife (and I really can't work out how) then you may have a case. You should still get duty of care from IB, but the extra costs should be handled by your travel insurance.