From the picture it doesn't look like its drawn back into its skeleton so that's good, personally I have found that sometimes it takes a little while for them to start to fully come out, my hammer doesn't like alot of white light, maybe u can move it off to one side and not directly under light, also, imo your salinity is a little low, don't know if this is an issue as up until recently I have been running mine low due to not calibrating my refractometer, was running minne at 1.023, I have since raised it to 1.026, the hammer took a while to come out and that may also have caused it, good luck