Media files titles hyphenating

Since the 8th September 2016 all my new media files, mainly images, are having the media file titles automatically hyphenated when first uploaded.

If I upload a file called My New Image; It is being changed to my-new-image automatically as a title.

Up to that date the Title would be My New Image

I am not sure what has happened but every file since that date is automatically hyphenating and I don’t want them to be. All media files prior to that date are still hyphen free.

I have changed absolutely nothing – the only Update of any note what the Jetpack Plugin.

Any ideas guys as it is driving me nuts and I certainly don’t want hyphens in my image titles.