The 3830R is marked as incompatible and probably won’t or can’t be fixed due to its Roku specs. Maybe Roku updated it to work, but I don’t know for sure. You may need to check with Tablo as to whether or not the 40R3BX KJ04X TV is compatible.
UPDATE: just found this in another thread…it appears Roku fixed the issue and you need to enable Audio Compatibility Mode… Roku 3830 incompatibility - #16 by TabloTV