Since Pie update, if music is paused on lockscreen for more than 15 seconds, headset button loses function until phone manually unlocked and Spotify opened and play pressed in Spotify app.
Hey @bbrooksby! Welcome to the Spotify Community. ^^
Please be aware that this issue is already under investigation.
Be sure to check this ongoing issues thread out to stay updated on this. Make sure to add your +VOTE. ^^
I'm not sure if you read my post very carefully. I don't think is the same problem. Maybe I should have mentioned that I have no problem with bluetooth.