The battery icon displays a question mark symbol instead of displaying the battery percentage. It does not appear to be detecting whether a power source is connected or not. $ upower -d Device: /org/freedesktop/UPower/devices/line_power_ADP0 native-path: ADP0 power supply: yes updated: Sun 02 Jun 2019 08:20:42 PM EDT (91 seconds ago) has history: no has statistics: no line-power warning-level: none online: no icon-name: 'ac-adapter-symbolic' Device: /org/freedesktop/UPower/devices/DisplayDevice power supply: no updated: Sun 02 Jun 2019 08:18:35 PM EDT (218 seconds ago) has history: no has statistics: no unknown warning-level: none icon-name: 'battery-missing-symbolic'
Thanks for including the command line output of upower. Unfortunately this means that the bug is in upower. The Xfce power manager only displays the values it gets from upower and in your case that seems "correct"... Please submit a bug upstream against upower.
Thank you. I have entered the bug against upower.