Hello Luke,

That is indeed a strange one... It  seems as if some other setting on the machine is preventing you from selecting the correct TA.

It may be a good idea to reset the Roadrunner back to factory defaults. You can do this by powering it up and holding the "1" button while the RR boots up. 

During the boot it will show you a message indicating that it is resetting to defaults.

When it is done booting you can try to set it to TA301 again using the "Common->Dig I/f->Def I/F" menu.  You will need to specify TA301 for interface 1 as well as interface 2. The Roadrunner will also be in loopback mode (factory default), which you can disable by setting the  "Common->System LB->Sys LB" menu to "none".

Please note that resetting to factory defaults will remove all settings from the codec and may also remove the speed dials.

Hope this fixes it!