Organisation custom logo field hidden

[chrisroos]

The "Custom logo" file input element isn't shown when choosing "Use custom logo for organisations exempt from the single identity".

Steps to replicate the problem:

1. Edit an organisation (e.g. https://whitehall-admin.integration.publishing.service.gov.uk/government/admin/organisations/cabinet-office)
2. Choose "Use custom logo for organisations exempt from the single identity" from the "Logo crest" menu
3. Observe the absence of the "Custom logo" file input field
4. Save the organisation
5. Observe that the organisation can't be saved because "Logo can't be blank"
6. Observe the presence of the "Custom logo" file input field

I would expect the "Custom logo" file input field to appear as soon as I choose "Use custom logo for organisations exempt from the single identity" from the "Logo crest" menu.