This is an old issue that I would like to revisit.
The headline states the problem, specifically, KOCE PBS for Southern California scans on my LG and Samsung receivers but not Tablo.
I have discussed this issue with tech support and in one case told it is a software issue and in another it was suggested that I hook-up the video coax directly from the antenna to Tablo to eliminate line loss when using the signal on more than one device.
The software issue would require some action on the part of Tablo and using a dedicated, direct, Antenna-Tablo video connection did not solve the problem.