A man entered the building on 23 April around 11am and was seen behaving in a suspicious manner before running off towards Bluehouse Lane.
The victim later noticed her mobile phone had been stolen.
The suspect has been described as Eastern European, in his 30s, of medium build with a round face and wearing a dark bomber style jacket, black trousers, white trainers, and large round sunglasses.
Officers investigating the incident are appealing for witnesses or anyone who has any information about the incident, to contact them on 101 or online at here quoting PR/45190042071.
You can also give information, 100% anonymously, to the independent charity Crimestoppers on 0800 555 111; or through their anonymous online form: https://crimestoppers-uk.org/