Shulker boxes placed over chests in 1.14.4/19w34a and 19w35a have varying results when placed facing up/down and sideways. In 1.13.2 shulker boxes place facing any direction are accessible and don't have the difficulties compared to newer versions. I assume this is either a bug or by design for whole block inventory blocks/tile entities compared to a campfire block which is accessible on top of a chest. Both single and double chests were considered and if a block was above either. After testing again (right before uploading the screenshot) I had a campfire alongside the shulker box and both chests below are inaccessible.