Hi PickleIsTickled,
Sorry to hear all of your previous Apex progress and cosmetics appear to be missing after moving from Xbox to PC. I understand how concerning that is, especially when you had a lot of content on the account.
Apex Legends progress is tied to your EA Account, and Cross Progression should allow you to access that progress across Xbox and PC as long as both platforms are linked to the same EA Account.
Please avoid unlinking or relinking any accounts for now, as this can affect access to your progress and content.
You can find more information here:
Please first check that both your Xbox and PC accounts are linked to the same EA Account that originally held your Apex progress.
If everything appears to be linked correctly and your old progress is still missing, please scroll to the bottom of the lost progress guide and select Contact Us so our support team can help check which EA Account your original progress is associated with.
I hope you’re able to get some clarity on where the original progress is stored.