I recently updated to 20.04 and I love the new full range of full color emoji but they disappear when I print, export to PDF or even if I download a pdf from email.
I thought it was a libre office issue at first until I noticed them disappear from the downloaded PDF. In the screencapture is a Libre office spreadsheet print preview screen full of emoji, and on the right is what I get if I export to PDF or print.

I have verified that "objects/images" is checked in LibreOffice, tried from a fresh file, and tried it in LibreOffice's safe mode. Please help.
43 Answers
Until this bug is fixed, the work arounds seem to be exporting to PNG rather than PDF or replacing the emojis with symbols from the Symbola font (which are black and white).
It was written, that it is a bug: 🤔
A valid workaround consists in uploading the LibreOffice file (eg ODT) to Google Docs and printing from Google Docs.
Not satisfying, but working.