Hi,
If a specific POS register is stuck on loading while others are working, here are a few things to check:
1. Check Previous Sessions:
    Go to Point of Sale → Orders → Sessions.
    Ensure there are no open/incomplete sessions for the problematic register.
2. Validate POS Configuration:
    Confirm that all Payment Methods, Journals, and Stock Locations are properly configured.
    Ensure no required settings are missing for that register.
3. Browser Cache & OWL Errors:
    Refresh with Ctrl+Shift+R or try opening POS in Incognito Mode.
    Open Browser Dev Tools (F12) → Console Tab, and check for any JavaScript errors (OWL component failures).
    OWL errors can occur due to:
        Custom POS modules or modifications.
        Missing images or product data.
        Corrupted browser IndexedDB cache.
    Try clearing browser Site Data (IndexedDB + LocalStorage) and reload.
4. Contact Odoo Support (Odoo Online SaaS):
    If the issue persists, raise a support ticket to have Odoo clear backend cache or check for corrupted data in the register session.
Hope it helps