Sorry, after going back in game they are now dropping as acacia saplings, no idea what happened there but it seems to be okay now.
I will try to do a video, I don't have mods installed if that's what is meant by a datapack.
No longer an issue in latest 1.15 snapshot and 1.14.4
Had the same issue but resolved following the guidance from @camden and @neewom.
Have to first click "go back" all the way out, you will see a new Microsoft login option, once you've found that you can delete the mojang one as it's no longer in use.