That's how Sportsnet+ premium works, so it's working as they advertise unless I'm misunderstanding something here.
If you're in the Ottawa region, the out of market hockey Sportsnet+ premium service won't give you access to Senators regionally broadcasted games on TSN5. They should be blacked out. You would need to subscribe to TSN Go to access them on TSN5 and leave Sportsnet+ out entirely.
That's why it works when you VPN to Vancouver as it's telling the app you're not in the Ottawa market, which is what that Sportsnet+ out of market premium service is for. The Sportsnet+ premium package is not meant for <insert canadian team here> fans living in the <insert canadian team here> region, it's meant for fans of those teams that don't live there, like say me in the Yukon trying to watch Senators games.
Like other streaming, this sports streaming is all a stupid mess and the monthly fees on these apps are absurd, but I don't think what you're using is technically working incorrectly.