Always in 'Charging' state, despite being disconnected from external power

[bigCamel]

I'd like to share some new findings, complementing @phuzy's observations.  

• No charger connected to either charging port -> PBP is always in charging state
  
• Charging via the original charger, then unplugging the charger from the mains socket but leaving the charger connected to the PBP. -> A couple of seconds after unplugging the charger from the socket, the PBP briefly changes state to 'discharging', then back to 'charging'.
  
• Charging via my phone's USB-C charger, then unplugging the charger from the mains socket but leaving the charger connected to the PBP. -> The PBP  changes state to 'discharging'. As soon as I remove the UBS-C cable, the state changes to 'charging'.
  

@Luke or @tllim, can you tell whether this is a software or hardware issue?