New Home Office regs have added an extra layer of red tape for non-EU international players who;
1. Cost less than £10m
2. Whose country is outside the top 50 FIFA ranking
...and he falls into this category, so you have to appeal the automatic bar with a strong representation on a "Special Talent" basis for work permit qualification, and once issued the international clearance is granted, player registered in the league .....then you're good to go.
Should be all sorted by close of play Friday hopefully. Trust me I'm ITK and act on behalf Arsenal in these sort of transfers.