I had the same problem. None of my workshop subscriptions were showing up. I looked around and found other people throughout steam having the same problem. Here are 2 of the solutions, however they didnt work for me. After a week, someone on here responded and told me the only other way was to "unsubscribe all" from your blueprints ( workshop). The downside you lose all your blueprints, but it works. I lost over 3000 blueprints so I know it can be tough lol

Soution 1 : Restart Steam and Planet Coaster in admin

Soluton 2 : right click planet coaster in steam library and select "properties", under the "local files" tab, click on "verify integredity of game files"

Solution 3 ( what worked for me) : Go to the main workshop page for planet coaster and on the right where it says "your files" click on your subscibed items and then you will see the unsubscribe button.

Thank You, i solved that way: i checked Unsubscribe all and make my collection again :0 . I love this game so much that i will sacrifice some time gladly. I wish that Frontier will add zoo and other features in next dlcs.