In palo alto like any some things are fixed with an restart.
1. If the managment plane in the masterd log (for more about the Palo Alto logs and their meaning you can check https://live.paloaltonetworks.com/t5/general-topics/knowledge-sharing-palo-alto-general-logs-and-log...) you see there are issues with a process or by using the commands "show system resources" or "show system software status" you a process down the this process can restarted/started ( debug software restart process xxxx ). For example with gui issue the web process is restarted and if it does not help then the managment server process is restarted. less mp-log masterd.log
2. Also the interfaces can be shutdown and enabled if there is an interface issue:
3. If this does not help and issues with processing client production traffic then on some devices then you can request only the data plane to be restarted. If this still does not solve the issues then a reboot or even shutdown (system halt) could be needed.
request datapane restart/request chassis restart slot
request system restart
request system shutdown
4.If the issue can't be discovered don't forget the ultimate solution for non hardware palo alto issues is saving the config to external storage then factory default reset of the firewall and again importing the the config (the TAC does this many times).