you may be having hdmi handshake issues. i sometimes have this when the roku is connected to my receiver but not when connected to my tv. i prefer the receiver connection to maximize my audio formats and not depend on the tv passing things through to the receiver.
i also have a chromecast that does the exact same thing. the fault appears to lie in the receiver.
when this happens, i find it best to remove power from the receiver and roku and plug them back in. give the roku time to boot all the way up before selecting its hdmi port on the receiver and all seems fine. in time i eventually see it again. i have noticed asking the reciever for info constantly may cause the problem again. overloading receiver during handshake? speculation but may be something similar with your tv. you might try power cycling your tv as i did my receiver.
hope this helps.
btw: my receiver and roku are HDCP 2.2 compliant. my TV is only HDCP 1.4 compliant.
i have no trouble with the TV.
I'd bet heavily the HDCP 2.2 handshake is the problem. knowing that does not help though...stuck with it.