Rated 2 out of 5 stars

I have done all this:
On order to use the add-on, turn off HTML composition (per account setting, Composition & Addressing → Composition → Compose messages in HTML format) and also make sure that "mailnews.send_plaintext_flowed" is disabled in the configuration (about:config). Furthermore, mailnews.wraplength needs to be non-zero

I get the little Line Wrap selection in the top right and it toggles off and on but I don't get any line wrapping.

I have two email accounts and both are set for HTML turned off for composition. mailnews is set to 72 and flowed false.

I have tried it on two different machines. One on TB 102.7.2 the other on TB 102.8.0

What else do I need to do?

This review is for a previous version of the add-on (1.4.1). 

Drop me an email, also reporting the TB version you are using, and then we can see how to debug this best.

I'm reading these reports from time to time here, but no one follow-up so far, and I cannot confirm the issue myself.