Well, first I wouldn’t use an optical cable for to the Pontus as you’re introducing additional conversions to and from light transmission and it’s limited to 24/96. Check the settings in the Oppo to make sure the digital outs are active and properly configured, and you also may want to try a 1m wire SPDIF digital cable in case the optical connection on either side is compromised (a regular analog RCA interconnect may work for this too just for trial purposes). Here’s a decent cable that’s not too pricey if you need one, and you can easily return it if it doesn’t work…
Good luck!