Hey, I have the same problem, but i did the ” select Post Name option under Settings > Permalinks “, but still doesn’t work,..
I press ‘add new’ portfolio, create a gallery from newly uploaded images and select photo gallery from the right hand side.
If fact If I preview the portfolio not working, all I get is “Page not Found”.
f you can show me your menu , I’ll appreciate it (With Screeshoots)