I have the same scenario as this archived post
I think it worked at some point since I specifically put comments 2 years ago in my 'Display Only' item to not remove it or change it from Never display...It is on page zero. The Success Message for my process is then set to my item &P0_MSG.
We are now on Apex 5.0 so idk if anything with upgrading caused this to no longer work or if that is just coincidence.
I pass the P0_MSG item to my code and build the success message in my package based on what gets ran...for every row I'm adding '<br>' at the end. I've also tried '</br>' and chr(13)||chr(10), but the line break still does not take affect. Is there anything else I can try, or a setting I'm missing on my Display Only item?

Thanks,
Janel