Sometime, if there is a threat to the clownfish in the tank, they are more likely seek protection of an anemone and more likely to go into a non natural host anemone.
Several times a day, put your clean hand in the tank away from the anemone and wave it around for several minutes. I find that this will get my Ocellaris and Percula go into my Malu, which is not a natural of these clowns.