So that I may look into this can I have your full model number? Also, have you tried a factory reset on the TV?
Have you tried changing out the batteries on the remote? Just to confirm when it searches does it look up the words that you said?
I have the same issue after updating firmware to 1294. I have performed a factory reset on the TV and that does not resolve my BIxby issue. The only thing I am able to do is ask Bixby about weather. Any other commands (i.e.: show source list) results in asking if I want to search the tv or web.