Missing page title on blog archive?

I'm at a loss here...

For some reason my blog post titles are not showing in the archive loop.

My CSS file has no reference to

.entry-title {
    display: none;
}

I have title enabled everywhere and indeed they even appear on the post itself - but I am at a loss why they wouldn't appear on the actual archive loop itself.

Any idea where to problem solve this?

I read in this forum to insert an <h1> in the post again but that would be weird have the title twice...

Any ideas where to look and solve this?

Thanks!