CMS API v1 doesn't recognize my collectionId as uuid

I’m developing a website to a client, and we’re using the CMS API to manage items inside Webflow CMS. But the v2 API was too buggy, returning me a status 0 randomly (sometimes i received a status 2xx, and sometimes a status 0), and also sometimes it said i was on my rate limit, saying my rate limit was 5 (even tho i’m on Business Plan).

So i decided to use the v1 API, but again it isn’t working, even in the own webflow page it’s breaking (List Collections). If i try to use the List Collections endpoint, it says on the parameter field that my siteId isn’t a uuid, and returns me a status 400 with “Unknown Error”, but if i use the v2, it works fine (sometimes). I really need to finish this integration, how can i solve this?