Home page only showing latest blog post?

This is a rather urgent problem that just popped up today. My home page is set to show all my blog posts. However, right now it only shows the most recent blog post at the top and no other posts.

The only thing I’m aware of that changed today is that my hosting provider changed my version of PHP (it’s now 7.1.24). I did install a plugin called FMTC Affiliate Disclosure but couldn’t get it to work properly and so I de-activated it. I have a plugin to insert code into headers and footers on each page/post, and I suspect that there was a conflict between this and the FMTC plugin. I’ve been running with the headers/footers plugin for quite a while with no problems. I use it for Google Analytics data. This may not at all be relevant, but I wanted to include it.