We've had reports from Legends that the Forest Portal has not been letting them through. This is a known bug - the Legends at PlaySide have been investigating it, and suspect it to be a memory issue on some devices.
The latest update 1.0.4 had some tweaks in it, and the upcoming 1.0.5 update will have more optimisations to let you through!
The team at PlaySide go over every bug report - a huge shoutout to the Legends who have been sending them in! If you find a bug in game, you can let us know here.