ok i figured this out finally after 15 minutes lol it worked fine and paused unpaused then would not unpause, just said cannot find music playback device named roku so i looked online and noone here had a solution other than resume or continue which had the same result. then i realized that the alexa was actually stuck trying to playback a music list i had started and told her to cancel. so saying unpause roku resume roku or continue roku was trying to continue playing the music but the roku cannot do that so she was confused. so i just said alexa continue and sure enough the last song started right where i had told her to cancel music well it was an 80's song list of over 50 songs so what i did to get her out of the loop was played a short song and let it finish now she can resume roku just fine - hope this helps and they need to fix alexa to actually cancel and forget something when you tell her too not save it until something else replaces it.
I don't know what the problem was but it does "unpause" now. You know Alexa -- she gets a bit picky now and then but she always figures it out. It is handy to be able to pause when I walk away for "a second" and then discover I need to do something else before I return to the TV, and then I can "unpause" without returning to my spot on the sofa.