That's because Warp charge is not supported on LOS.Two things that bothers me: charging is slower than on stock OOS (It took me 1 hour to charge 9 Pro from 20 to 100℅ while on OOS device is charged from 0 to 100% in 40 minutes) and device shows me 1 hour and 24 minutes until fully charged all the time while charging
Btw why do you want to switch to LOS? It's not better than LOS. Unlike dead Cyanogenmod, LOS has no any additional features or additions.
And you are getting worse launcher + worse camera app + some things not working.