nice looking aneome- if im not mistaken they usually will move around if they arent happy with current conditions- so it could be flow, light, or water related etc. My guess would be that its reaching for some more light. Hopefully your clown will start hosting it soon to protect it from your shrimp- my peppermints are viscious, but they dont get a chance to touch my bubble with the clowns on guard. I would try to distract the peppermints with a piece of food when you feed the anemone to give it a chance to hold on to the food before the shrimp steal it. You may want to move a piece of live rock with a good spot for the anemone's foot to anchor into near it. The hatians like strong lighting and flow if im not mistaken.... hope this is of some help.
Good luck! and nice tank
