k95 rgb platinum "Plus" key on numpad registers multiple keys

Hello everyone. I have a strange problem. While the rest of the keyboard works fine when I press to "+" key, it registers multiple keystrokes.

Here's a simple log from keyboard test:

37:02.0317 Num + (0x6B, BIOS 0x4E) DOWN
37:02.0328  (0xB2, BIOS 0xE000) DOWN
37:02.0331  (0xB2, BIOS 0xE000) UP -> 3ms
37:02.0333  (0xB1, BIOS 0xE000) DOWN
37:02.0334  (0xB1, BIOS 0xE000) CHATTER DETECTED -> 3ms
37:02.0337  (0xB1, BIOS 0xE000) UP -> 4ms
37:02.0339  (0xB3, BIOS 0xE000) UP -> 2ms
37:02.0345  (0xB0, BIOS 0xE000) DOWN
37:02.0346  (0xB0, BIOS 0xE000) CHATTER DETECTED -> 5ms
37:02.0352  (0xB0, BIOS 0xE000) UP -> 8ms
37:02.0357 Num Lock (0x90, BIOS 0x45) DOWN
37:02.0361 Num Lock (0x90, BIOS 0x45) UP -> 7ms
37:02.0362 Num / (0x6F, BIOS 0xE035) DOWN
37:02.0369 Num * (0x6A, BIOS 0x37) DOWN
37:02.0373 Num / (0x6F, BIOS 0xE035) UP -> 10ms
37:02.0382 Num * (0x6A, BIOS 0x37) UP -> 12ms
37:02.0384 Num - (0x6D, BIOS 0x4A) DOWN
37:02.0390 Num - (0x6D, BIOS 0x4A) UP -> 5ms
37:02.0394 Num + (0x6B, BIOS 0x4E) UP -> 79ms

As you can see, besides "+" it also registers num lock / * - and enter. For the records, the press also mutes the sound as well.

Any idea why this happens?