Am i being dumb? Can't run tidal basin on normal

I'm trying to do my stage 5 step for firewall spec and i need to blind wyvern twice, semi easy tbh. But the problem i have is my 2 options are manhunt and invasion for tidal basin.

Do i need to clear the invasion before i can do it on normal? The reason i ask is to clear it i need to complete 3 invaded missions to unlock invaded district union, clear that then invaded tidal basin opens up, then clear that to do it normal?

Seems ridiculous to just be able to do it on normal again.

So am i daft on this one or am i looking at 2-3 hours of redudant tasks to just complete 1 objective?