The charging bug is still here in LOS 19.1, according to @EskeRahn.
This acredite a hardware problem with the battery regulator, I know I can charge twice before reboot, the first and second time it drops in maximum 10-15 minutes, the third time I will have to reboot as it doesn't charge anymore.
This happens a few time and begins one year ago but it's worse now. On the other hand I used LOS16 without problem, but the battery was not so old.
But....Interesting fact, it's charging without problem to 100% when the phone is off.
edit : I'm pretty sure there was no charging bug in LOS1