This has bugged me several times now: I frequently add a page excerpt macro, containing some lines or paragraphs of text, followed by another paragraph of text - outside the excerpt macro body. During edit mode, both elements appear as two separate paragraphs/blocks.
However, when (pre)viewing the content, the excerpt content and following paragraph are just concatenated as illustrated below (see how there is not even any space after the "." as highlighted in red):

Is this a defect? Is there a way to have the paragraph following the excerpt block be displayed as a separate paragraph?