Saw this over in the bug section:
https://forum-en.gw2archive.eu/forum/support/bugs/Can-t-forge-Invader-exotic-items
And my memory is fuzzy, but I could have sworn you were never able to use the mystic forge with WvW exotics … Rares at one point yes, but never exotics …. But I think I tried it a long time ago and it could have changed since …. So I thought I’d ask you all.
L’enfer, c’est les autres