The local network section doesn’t use CIDR notation, so no /24. You’ll have to use 192.168.1.0/255.255.255.0
Also, as noted here: Plex Agent no longer working and Add to Watchlist option is also now gone - #85 by Fyb3roptik there may be an issue with attempting to use the loopback address (localhost also references 127.0.0.1) with PMS as of late. Use the actual IP (192.168.1.whatever:32400/web) and see if that gets you where you need to be.
