Welcome, and thank you for posting here in the Roku Community, @Skott47a!
I appreciate your precise explanation of your concern about being able to control the power of your TCL Roku TV using your Roku remote. No worries! I'd be happy to help.
Is this the remote that comes with your TCL Roku TV, or was this purchased separately? Also, have you been able to control the power of your TV before? In the meantime, we can try resetting your remote by pressing and holding the Back and Home buttons simultaneously for about 20 seconds. After doing so, pair it again to see if this helps.
If the issue persists, we can try plugging your Polk Audio sound bar into an optical cable to see if this makes any difference.
I'll be looking forward to your update!
Best regards,
Carly
Carly Y.
Roku Community Moderator