Why does PleX pick up less channels than my TV?

I have a WinTV Quad HD tuner setup with PleX media server. If I connect my antenna directly to the TV, there are at least two more channels that get picked up compared to when I connect it to the winTV tuner (all other things being equal, of course - antenna in exact same spot + direction).
Why might this be happening? Is there anything I can do to make PleX pickup the channels?

It can be a couple things:

For Gracenote EPG issues report them here You can try a different EPG and see maybe its missing in gracenote?

I believe you can just make you own custom mappings if you want as well.
To setup your own custom XMLTV file use using something like MC2XML try this

It’s not Plex’s fault. It may be the tuner setup you are using in the PC. It may be the cable run (assuming you are using a different cable run for the TV vs the WindTV Quad HD tuner. Multiple issues can affect tuner strength. I use HDHomerun Connects. Even different hardware generations and firmware versions of these devices can affect which channels are succesfully tuned in. Plex is just reading from the device what channels the device can tune in successfully. If the device can’t tune in the channel, Plex can’t record it.

@rodgerzeisler said:
It may be the cable run (assuming you are using a different cable run for the TV vs the WindTV Quad HD tuner.

So your assumption about the cable is incorrect - I used the exact same cable for both, just switched it back and forth.

However, you mentioned a good point:

@rodgerzeisler said:
Plex is just reading from the device what channels the device can tune in successfully. If the device can’t tune in the channel, Plex can’t record it.

I didn’t have the antenna properly pointed when I scanned for channels with the WinTV application. I figured Plex would pick up more channels, if any, when I scanned in Plex. Turns out thats not the case. I had to rescan for channels in WinTV, and then scan in Plex to pick them up.