I recently added LibreOffice to my home computer because it is what we use at work. A daily task I perform at work is to email reports from spreadsheets exported from a CRM. I clean them up in Calc and paste them into a Gmail. At work, the grid lines remain in the email so everything looks clean. I have been doing this since the beginning of 2012.
When I attempt to do the same thing at home, the formatting disappears and it looks like the information is pasted as plain text. I’m not pasting as plain text. I always hit ctrl-v or right-click and select paste. It works fine at work.
The version I am using at home is newer (126.96.36.199) than the one at work, as they do not allow updates on our network at work.
I used to have this problem at home when I used MS Office Excel, which was another reason I switched to Libre at home, so I can avoid having to do multiple steps (the excel “solution” was to paste it into a word doc and then recopy it, allowing you to paste the formatted data into a gmail allowing it to remain intact).