I think this is a wiring problem. IIRC (and I don't have a diagram in front of me) injectors 1 & 3 , and 2 & 4 are fired in pairs on a single circuit. Looks like you have one circuit with a dodgy connection that has knocked out two injectors.

I've had loads of injectors cleaned and never had a problem. I've never even had to tap one before.

You could test by swapping them around with 2 & 4, or just connecting up another spare injector to see if the injector clicks..