The company is not showing because user-permission is also applied on “parent_company” and “existing_company” field inside company record. In your case, mostly those are set as blank. I am assuming in System Settings, you have enabled “Apply Strict User Permissions”, due to which the company is not showing as company is not matching for parent_company and existing_company field.
I have send a fix to ignore user permissions for parent_company and existing_company fields. https://github.com/frappe/erpnext/pull/21010
Until the fixes released, you can enable “Ignore User Permissions” property for those fields from Customize Form -> Company.
Or you can disable strict user permissions from System Settings.