Hi! Can you please specify if you're using a mobile device when you're typing a comment? 

Just happened to me. Am using a Samsung Galaxy S7 

 it happens all the time, thats why i have to check the preview b4 posting and i've tried it on laptop & samsung tablet

hello commanders 

it is a known bug where posting from mobile devices always deletes the last sentence 

here is a simple but annoying workaround :-

after you finish typing what you want click enter and type few random letters ( anything ) and then post it 

the new ( anything ) sentence will be deleted and your post will be safe :))

Thank you for your comments, Commanders!