I get an alert that they have reacted to the message but no actual graphic display. I am assuming this will probably be fixed in the stable release but that's just my speculation:)
messages app > settings (in the triple dot menu, top right in the search bar) > advanced, make sure show iPhone reactions as emoji is selected. If so, go back one page, chat features and make sure features are enabled. Not sure if that's related but it can't hurt.
If both those are on, try clearing the cache (bring up the multitasking display, tap the app icon>app info>storage>clear cache and see if that helps. Failing that, report it to Samsung and wait for beta 3.
The iPhone emojis don't follow RCS as Apple doesn't support RCS so all messages to an iPhone user will be a normal text message
Google found a way to read a reaction an iPhone user makes and show it on Google messages (it only works for text messages, pictures don't work at this time)
I'm having the same issue with the emojis on the second beta. And I do have the reactions as emojis setting turned on and am connected to chat features for RCS.
