I’ve managed to solve the issue this morning following this https://community.shopify.com/topic/1231086
To summarize, logout the theme with Shopify CLI command ‘shopify auth logout’, then logout from shopify and partner dashboards (before check if you have the owner status if it’s a development store). Then login to Shopify and Partners Shopify (using the same account of course) and retry the command ‘shopify theme dev --store {shop}’
On my side, it solves everything.
Good luck