Error Message? Portfolio homepage gone? Says "The current template does not support page pages"

I've been trying to rebuild my Portfolio on Squarespace 7.1 (I built my previous website in 7.0, 7 years ago, and can't seem to upgrade it to 7.1 without starting from scratch. I want the mobile editing view capabilities.) I was using a suggested template for a portfolio and it was going pretty well, until my homepage errored out and is saying the template doesn't support 'page pages.' I don't think I had done anything new except change some site style (type, colors, etc) when that error message popped up. Does anyone else encounter this or know what it's happening? I'd hate to start all over. Below is what the 'homepage' which used to have images of all projects, now looks like.

You try log out account, login and check again

I've just had exactly the same issue. Please tell me this issue rectifies itself? I've spent 2 weeks putting together my whole portfolio and now it's apparently disappeared.