I've not tried to move an immature bush, so just taking a random stab. Was it fully grown? Which bush are you trying to move? What terrain is the bush on? Screenshots may be helpful showing the problem.
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It was located on a snow tile. Vatas has it. I just figured that out by experimenting. I thought that might be it. Some of the snow melted and I can move a couple of bushes now, but not the rest. I can't dig to remove the snow when there is a bush on the tile, so either I chop the bushes or wait until spring thaw is complete.