Roku Ultra (the problematic one) reset back to factory. Removed all apps that are “preinstalled” including Tablo. Checked wifi/network hidden screen, still have problem. Likely the router itself and/or configuration.
Added the Tablo channel, and is the only channel. “Full” Channel list is being displayed, either something has survived the factory reset, or the channel is pulling configuration data from the uSD and/or the Tablo 4.
The hunt continues.