Run/Stop Key does not stop Ulitmate II+ Cartridge from stopping and exiting from playing SID file on NTSC C128DCR

[megaman85]

Wierd issue I discovered on my NTSC C128DCR with the Ultimate II+ Cartridge- when playing sid files and I press run/stop key, it does not exit the sid file playing but instead it causes the borders to flash and if paused by presssing space bar, pressing the run/stop key changes the borders of the screen.
On my flat NTSC C128 and breadbin NTSC C64, when playing sid files from ultimate + cartridge, when pressing run/stop key, it exits from playing.
Can anyone replicate this issue or explain or have a solution?
I'm running the latest firmware 3.11