Mock Orange is a shrub. It needs space to develop roots and plenty of water - perhaps it is too near the wall, so that it is too dry and cannot get roots down deep because of foundations?

West facing wall sounds good to me for it to flower. I would move it in October a little further from a wall and give it lots of feed next spring.

One reason why philadelphus don't flower is that they flower on second year growth so if you're pruning it in spring or after late summer it won't flower next year.

Once it does flower, prune immediately after flowering if required. I prefer to take out about one third of the brances each year so that it flowers well on the other two thirds next year.

Thanks for the pruning advise . Think I will move it in October also.