[jonfields45]

Old fashioned fluorescent lights are the most likely generators of the electrical interference. Are there any in the room where you play the guitar (or directly underneath the room)? Over the last 40 years I've played two gigs, both country clubs, where the stage area had an unstoppable interference into our guitars. Luckily we found ways to get through the gig (by holding our guitars in just the right orientation the buzz was tolerable).

If the guitar used to play fine and now doesn't, then something changed and the shield on the Matrix UST can get compromised and become susceptible to noise. If you search the AGF there are threads where people were somewhat successful diagnosing the rip in the shield and improvising a repair. Replacing the UST is the obvious first thing to try if you're hiring a tech to do the work.