Yes indeed. Bled it all this morning and the boiler ran OK after that. Will bleed it tomorrow etc. etc.I find with central heating systems there's often air left in them even though water's coming out of all the bleed nipples, so it helps to let them settle overnight and bleed again, run the boiler and bleed them again and so on. Plus there's often a lot of air in mains water, either fully dissolved or in those tiny bubbles that give it a cloudy appearance, so it's not surprising that air appears even after you think you've got rid of it. Patience and repeated tweaking will serve you well in the long term.
I was amazed at the accumulated crud in the horizontal section of pipework we removed to put the magnaclean in. The 28m bore was down to 15mm and it had to be chipped away with a metal implement.
The vertical piece (by contrast) was as clear as can be.
TBH I am not sure how effective the inhibitors/cleaners are, but they must do some good.