Devices no longer scan for channels

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2022-09-24 19:41:21.202 [DEBUG][4] FindFilterByName failed to locate filter: Silicondust HDHomeRun Tuner 1070C7FD-3
2022-09-24 19:41:21.203 [ERROR][4] Unable to locate tuner filter (Silicondust HDHomeRun Tuner 1070C7FD-3)
2022-09-24 19:41:21.207 [ERROR][4] Unexpected error: System.NullReferenceException: Object reference not set to an instance of an object.

Your tuners are not available in your system, so NextPVR is unable to use them.

ie, I'm not sure if you've uninstalled the SiliconDust drivers, or it's happened because you've updated the SiliconDust software, or whether the drivers can't detect them on the network so isn't creating the tuners. Maybe restart NextPVR (or your machine), then look on the Settings->Devices page to see if they're listed, and whether they're marked 'unavailable'