Hi thank you for your reply.
I have attempted to insert the IO shield properly but only managed to get the two middle sides in. The smaller opposite ends of the io shield still sticks out but I am able to secure the motherboard on without any problem.
Will this be a problem in the future?
Thank You
Leaving it as-is will put more pressure on some of the connectors than usual. But while it probably won't be a problem it's also hard to say with certainty.
It can be a bit difficult to pop it in sometimes, but if you absolutely can not suggests the cut-out in the case isn't the correct dimension....possibly from an extra thick coating of paint. I'd have trimmed it before assembly with a metal file...or even just scraping the paint off if that's the case.
If you do decide to trim the ends with a metal file so it fits better you'll need to competely remove the motherboard and other parts. You need to thoroughly clean out the fine metal dust that filing will leave behind.