I have just got a Spider Classic 15 amp for (early ðŸ˜) Christmas present.
I had my guitar plugged to input, my Google pixel 2 phone to cd/MP3 input and my headphones on the output.
I could hear the guitar fine on its own, and I could hear the song from my phone playing fine on its own. When I tried to play along with the song I couldn't hear my guitar. It's like the song takes priority over the guitar and cuts off its output. When I turned off the song, the guitar was fine again.
Kinda weird, and I have no idea what to do to sort it. I played around with ask the settings and turned it off and on and it stayed the same.