I’d tell them the order is right: nutrients → EC → pH, but a big EC drop after pH adjustment isn’t something I’d consider normal. 👍
pH Up/Down usually changes EC only a little because you’re adding a tiny amount of dissolved ions. If EC is dropping dramatically, I’d first suspect the measurement rather than the nutrient mix: stir thoroughly, give it a few minutes, then measure again. Also make sure the EC probe is clean and calibrated and that both readings are taken at roughly the same temperature.
I wouldn’t add extra nutrients afterward just to chase the original EC number—you could end up overfeeding based on a dodgy reading.