John, A couple things for you to think about....
First, check the wiki for useful articles: Logs, debugs and files which are useful when troubleshooting and resolving issues in NMIS
Next check these things...
Consistency - Are you loosing graphing on everything at the same time, or only sporadically on different devices/interfaces. Most likely the device is overloaded.
Check Your Logs - If you're running our VM you will find the NMIS logs in /var/log/nmis, look for nmis.log and see what events are happening during the time period when the graph issues occur.
NMIS Performance - from the NMIS interface select System->Host Diagnostics->NMIS Runtime Graph. Compare NMIS' performance during these time periods.
The Runtime graph is a great place to start, it will tell you how long your collect/update cycles are taking which could be the problem. The logs should have good information on what NMIS encountered when trying to get/save the snmp data during the time periods where it is not appearing in your graphs.
I cant see any stuck processes. See screenshot below:
I hope this was what you meant.
Its an NMIS8. Please see screen grab below
Hello John, I'm sorry to hear you're having problems with your NMIS installation. Can you let us know what version of NMIS you are running, and perhaps include a screen cap of what you are seeing? Also, please check your nmis.log for indications of stuck processes or other issues.