Howdy, @LukeStephan! Thanks for writing in…it appears you’re using the Posts (Minimal) Element for your blog index, which does feature an automatic excerpt generator in its Text Element, which is powered by the {{dc:post:excerpt length='20' fallback='No excerpt'}}…
Dynamic Content string inside that Element. This should automatically generate an excerpt that is 20
words long for you based on the content of your Post.
I have tested this Element locally and created a new Post, which I first did in a standard fashion (just writing content in the WordPress editor) and then also using our Builders to structure some content within. In both cases, an excerpt was automatically generated for the Element and outputting as expected. The Manual Excerpt that @tristup mentioned is really only available if you want to create a custom excerpt that should overwrite this automatic one, which doesn’t seem to be working on your end at times.
I believe we fixed an issue related to excerpts not being generated in “structured content” (i.e. content made using our Elements) yesterday, so if you have not done so yet, please update your theme to the latest version from yesterday and see if that addresses this issue of your excerpts not being generated. If you are still experiencing an issue after that, let us know and we will go from there.
Thanks!