My sister is constantly doing deliveries to the printers in that same complex and told me about it. She gave me the same information that John has posted, possible dodgy wiring within the hobby shop's premises. Apparently the current owner of the hobby shop was emotionally gutted as he had a lot of personal items stored there, including some models he had built when he was young(er)...
She took this shot of the place and sent it to me. Not a great shot because it's from a phone, but it gives you some idea...
Good to hear it's had minimal effect on UAS, John.