Mask opacity reverts to 50% after repositioning the image

Trying to create a template with 3 images (also just one image Using a mask to limit the size of the image, so I can reposition etc. I have added a border and a shadow. Changed the default mask opacity from 50% to 100%. Made the image a placeholder. I then experimented by repositioning the image within the mask and the Mask opacity reverted to 50% and then stayed at 50% so each time I reposition I have to reset the mask to 100%

The mask was set to 100% opacity then the image was repositioned and the mask opacity deflated back to 50%. I can understand why it should temporarily go to 50% so you can reposition but it should revert back to 100%