This is a tough one to describe, as it is somewhat conditional.
Using Views as blocks. The view is of a Content Type with three sections (not using Paragraphs or Field Collections), each with a image field with a default image and a formatted text field. If the text field is present it is re-written with an element for the Background Image Formatter to target (targets use unique css identifiers - the Image field is not included in this and no Tokens for the Image field were used).
When a user is anonymous, everything is fine and all background images are displayed in all possible variations (one, two, or all three sections).
When the user is authenticated, then there is a much different behavior. If only one re-written field/element is rendered then the background image is rendered. Reviewing the page source shows all three style tags in the head with the correct css settings. If more than one field/element is rendered then no background images are visible and the style tags have not been rendered in the head of the document.
It does not matter if the logged in user has access to the admin toolbar or any other drupal overlay things. All permissions are install default and it doesn't matter if the user has any elevated permissions. (Can it be permission based if it works with one image but not multiple?)
Module was originally installed as 1.6, but has been updated to 1.10 with no change in behavior. On Drupal 8.7.1.
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Edits: add correct module version & add drupal version & a word.
More edits: I've been digging around the module and I can see it is building the elements correctly in viewElements() for all cases, and firing when required.