"Sign in or renew subscription" for owned game

I played and finished Subnautica back in January of 2019, and left it installed on my console because I knew I'd be back to it eventually. Wanting to revist the depths, I started it back up and was immediately greeted by code 0x803f900a, "Sign in or renew
the subscription: Sign in with the profile used to buy this game, and make sure your subscription to Xbox Live Gold or EA Access is up to date." Having already bought the game originally as a digital download (for $30 if I recall), I figured this was a fluke
and cold-started my console to manually sign back in again. Same error on game startup, so I began looking through forums for a fix. The full game was still installed, I remembered distinctly playing it and have a slew of achievements with dated screenshots
to prove it. I even finished and "won" it. I didn't buy it through Xbox Live Gold or Game Pass originally; in fact I didn't subscribe to any service until February of 2019 once I finished Subnautica. A lot of the forum responses for that particular error
code suggested to delete and redownload the user profile to the console, and barring that, delete and redownload the game itself. The former got me nowhere, so I attempted the latter. When I went to re-download it, I got the "purchase" prompt instead of the
download option. I checked the review tab and was met with "you don't own this game and therefore cannot post a review". The kicker is now it isn't even in my purchase history! In fact, there's a gap between when I bought and completed the game from early
January to late February of 2019...what gives?

I'm the only one in my household who uses my console, and am (and have always been) the only profile on it. I'm really not sure what else to try, and would prefer to not have to shell out *another* $30 for a game I already owned. Any suggestions?

Thanks in advance.

:)