Just got this problem with one thumbnail size. If I modify it, it creates another one with the same name and the properties I choose(crop, etc).
Later sizes created after that are deleted properly. Only this one somehow won’t go away. If you delete it, it disappears from the Image size area, but you can still see the entry for it in the thumbnail regeneration area + get php button also returns the settings.
One more strange effect: Normally ‘size’ is appended to the name of the Image size specified, e.g. when you create a new thumbnail and you enter ‘Feature’ in the input box, it becomes ‘Feature size’
Now the size is entered at the beginning of the name, so it becomes ‘sizeFeature’, without spacing in between as well.
Delete the plugin directory manually, reinstall – that custom size comes back! How is this happening?
Perhaps some settings are saved in an area not in the plugin directory or something? Or has the plugin somehow permanently added this thumbnail size? Seriously, if the author is reading, can you help with this?