I can't play the full album when the device has a password lock and uses the Neutron or NePLAYER app

I use iPhone X IOS 14, when the screen is off and the iPhone has a lock password and play music using Neutron or NePLAYER application, after the song is playing, it will stop without continuing to another song in My Album . I tried disabling the lock password and it works fine again. My machine cannot fail to set a password. Please help me to set the password and play music normally. Previously I used iPhone 11 IOS 14.3 also had the same situation. Please help me, best regards!