I have reproduced this.
i will try it later on a full Roku Stick.
Loads, but does not run, on Roku Express 4K and Roku Streaming Stick+
Loads and runs on Firestick 4K Max
App not available from LG Content Store.
So not a Now issue per se, as it seems to be a wider Roku issue.
I think you should get in touch with NHL and report these findings, and let them sort it out.