@drdan I think you might be confusing bookmarks and Speed Dials. Bookmarks are text links in the bookmarks section of the Opera menu. Speed Dials are the square icons on the Opera home screen. Bookmarks sync automatically but speed dials don't.
Although Speed Dials are separate on each device and don't automatically sync, you can import speed dials from your other devices. To import a Speed Dial, tap the icon at the bottom of the speed dial page that looks like a phone in front of a computer monitor with a star in the middle of it. Tapping that Icon will open an "Other Speed Dials" page showing you your Speed Dials on other phones. To import a single Speed Dial, do a long press on it and choose Import. You can import all your Speed Dials from another phone by taping the 3 dot menu at the top right of the "Other Speed Dials" display for that phone and choosing "Import all"
Bookmark sync works for me. I have Opera for Android on multiple phones as well as Opera on my PC. I have bookmark sync enabled and all my Opera bookmarks are all synchronized across all my devices.
If bookmark sync isn't working for you, I suspect it might be because you are running an old version of Opera Android as the current Version 47 does not have the heart icon you mentioned. Try upgrading to the current release to see it that resolves the issue.