I will provide a recipe for the problem that is happening.

1 - Open Emacs

2 - switch-buffer to the Scratch buffer

3 - Copy the following snippet

Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.

3 - Paste on the scratch buffer. It should look like this:

;; This buffer is for text that is not saved, and for Lisp evaluation.
;; To create a file, visit it with <open> and enter text in its buffer.
    
Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.

As an image:

4 - Now, put the point at the beginning of line 4, right before the first word Lorem.

Execute command forward-sentence. Notice the cursor goes to the end of the paragraph!

I was expecting it to go to the position just after the first full-stop punctuation mark on industry.

Did I miss something?

I reproduced this recipe after starting Emacs as Emacs -Q. Thus, I do not think this is related to my config file.

This question is related to a previous doubt.