Samsung S9+ disconnect bluetooth headset when call waiting

[Android Central Question]

Brand new Samsung S9+ connected to Plantronics PLT_500 bluetooth headset. Before, same day, everything works fine no matter which mobile phone was connected to PLT_500. During very first call with S9+ I received other call but there was no ringing or any other notification on my headset (that I had before), it was disconnected from PLT_500 and on the screen was sign that bluetooth is active.