Hi,
Have you checked that the BT drivers in the the computers are up to date?
According to the [https://www.tronsmart.com/products/tronsmart-element-mega-bluetooth-speaker|Tronsmart Eleement Mega FAQ] (see #23) :
''We can’t supply any drivers. The Bluetooth A2DP/HSF drivers may be required to play stereo sound via Bluetooth connection. But the driver is actually needed for the Bluetooth module on your PC, instead of the speaker. The different Bluetooth module may require different drivers. Please contact your PC or Bluetooth module's manufacturer for the driver update''.
It might be worthwhile checking this out and see if there are any updated drivers for the BT module in both the computers