I just had to say that this plugin " strapi-plugin-populate-deep" has been a major relief. The population system by strapi default is extremely confusing and frustrating especially when you get to dynamic components with media items. This capability needs to get merged back into strapi.
I went from this.
'populate[authors][populate]': '*',
'populate[seo][populate]': '*',
'populate[thumbnail][populate]': '*',
'populate[alsoCheckout][populate]': '*',
'populate[alsoCheckout][on][__articles.podcast]': '*',
which the thumbnail was still not loading to just this…
'populate': 'deep'
and it just works!