I cannot get the check mark to turn green so I cannot return a bush, there’s no room what should..

Until the glitch is fixed such that gift bushes will automatically find an empty space, you'll have to manually move the bush to an empty space yourself. If you are able to select a bush, then there is a space available, though it may still be hard to see.

This trick may help. When visiting an island, close the bush menu. Move to another area of the island that may have a space. Try to give a bush. Sometimes it may find an empty space in the scene. Other times, you'll have to try again at another area of the island.

If you have tried and just can't find a space or there is truly no space available (all bush buttons become gray), then you'll just have to try again another day.