PC doesn't recognize games from Xbox as owned even though i bought them.

It'll depend on what games they are. Only games that support Play Anywhere will allow you to install them on PC without having to purchase them again for PC.

If you're going to buy the Season Pass, buy it from one or the other. Once the episodes come out though, DO NOT buy them from the Xbox Marketplace as you will be charged. Instead, go to the store in-game and download the episodes for free where it will recognize
you bought the season pass. Doesn't matter if you bought the Season Pass from Xbox Marketplace or the in-game store, it will recognize it either way.

*SPOILER ALERT FOR THOSE WHO HAVENT PLAYED YET*

[MOD REMOVED]

I am having the same issue even though everything was bought under the same Xbox Live account. Part of my problem is that the purchase of the Expansion Pack doesn't show up in my purchase history or the purchase history of the other accounts on my Xbox...
even though the console knows I own them and can play them.

I bought it with the console, just like all my other dlcs for this game and the game itself. Its never been an issue using them on pc with play anywhere, but now even though it says owned and theres an install button it always says error when trying to
do so

Hi and thanks for reaching Microsoft Xbox gamer's community. My name is Josef.
I'm an Independent Advisor and a Microsoft Xbox user like you.

Hope you're doing great today Tech.2

Unfortunately that's not possible. You need to download the games again on the other PC

The Xbox app doesn't recognize yet installed games from another PCs even if the account is the same.
Each game is encrypted and each PC has like an ID to recognize this game